diff --git a/pkgs/racket-test-core/tests/racket/path.rktl b/pkgs/racket-test-core/tests/racket/path.rktl
index bba18722f7..85cc96ca54 100644
--- a/pkgs/racket-test-core/tests/racket/path.rktl
+++ b/pkgs/racket-test-core/tests/racket/path.rktl
@@ -497,6 +497,21 @@
   (check-cleanse cleanse-path)
   (check-cleanse resolve-path))
 
+(test (bytes->path #" .  " 'windows) normal-case-path (bytes->path #" .  " 'windows))
+(test (bytes->path #"\\ .  " 'windows) normal-case-path (bytes->path #"/ .  " 'windows))
+(test (bytes->path #"\\ .  " 'windows) normal-case-path (bytes->path #"\\ .  " 'windows))
+(test (bytes->path #"x" 'windows) normal-case-path (bytes->path #"x .  " 'windows))
+(test (bytes->path #"\\x" 'windows) normal-case-path (bytes->path #"/x .  " 'windows))
+(test (bytes->path #"\\x" 'windows) normal-case-path (bytes->path #"\\x .  " 'windows))
+
+;; Make sure `normal-case-bytes` leaves unencodable bytes alone;
+(test #"\340x" path->bytes (normal-case-path (bytes->path #"\340x" 'windows)))
+(test #"\340\340x" path->bytes (normal-case-path (bytes->path #"\340\340x" 'windows)))
+(test #"\340x" path->bytes (normal-case-path (bytes->path #"\340X" 'windows)))
+(test #"\340x" path->bytes (normal-case-path (bytes->path #"\340X . " 'windows)))
+(test #"\340x\340x\340" path->bytes (normal-case-path (bytes->path #"\340x\340x\340" 'windows)))
+(test #"x . \340x" path->bytes (normal-case-path (bytes->path #"X . \340X . " 'windows)))
+
 ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; \\?\ paths in Windows
 
diff --git a/pkgs/racket-test-core/tests/racket/unicode.rktl b/pkgs/racket-test-core/tests/racket/unicode.rktl
index 71ca0276a8..7658ad86ac 100644
--- a/pkgs/racket-test-core/tests/racket/unicode.rktl
+++ b/pkgs/racket-test-core/tests/racket/unicode.rktl
@@ -1194,6 +1194,10 @@
       (stest #f string>? "b" "\uE2")
       (stest (if c? #f #t) string-locale>? "b" "\uE2")
       (test "ABC" string-locale-upcase "aBc")
+      (test "" string-locale-downcase "")
+      (test "a" string-locale-downcase "A")
+      (test "" string-locale-upcase "")
+      (test "A" string-locale-upcase "a")
       (test (if c? "\uE2" "\uC2") string-locale-upcase "\uE2")
       (test (if c? "A\uE2\0B" "A\uC2\0B") string-locale-upcase "a\uE2\0b")
       (test (if c? "A\uE2\0\uE2\0B" "A\uC2\0\uC2\0B") string-locale-upcase "a\uE2\0\uE2\0b"))
diff --git a/racket/collects/racket/private/for.rkt b/racket/collects/racket/private/for.rkt
index 68a7a3b36f..60cb98c7dd 100644
--- a/racket/collects/racket/private/for.rkt
+++ b/racket/collects/racket/private/for.rkt
@@ -902,17 +902,17 @@
 
   ;; Vector-like sequences --------------------------------------------------
 
-  ;; (: check-ranges (Symbol Natural Integer Integer Natural -> Void))
+  ;; (: check-ranges (Symbol String Natural Integer Integer Natural -> Void))
   ;;
   ;; As no object can have more slots than can be indexed by
   ;; the largest fixnum, after running these checks start,
   ;; stop, and step are guaranteed to be fixnums.
-  (define (check-ranges who vec start stop step len)
+  (define (check-ranges who type-name vec start stop step len)
     (unless (and (exact-nonnegative-integer? start)
                  (or (< start len) (= len start stop)))
-      (raise-range-error who "vector" "starting " start vec 0 (sub1 len)))
+      (raise-range-error who type-name "starting " start vec 0 (sub1 len)))
     (unless (and (exact-integer? stop) (<= -1 stop) (<= stop len))
-      (raise-range-error who "vector" "stopping " stop vec -1 len))
+      (raise-range-error who type-name "stopping " stop vec -1 len))
     (unless (and (exact-integer? step) (not (zero? step)))
       (raise-argument-error who "(and/c exact-integer? (not/c zero?))" step))
     (when (and (< start stop) (< step 0))
@@ -939,7 +939,7 @@
       (raise-argument-error who type-name vec))
     (let* ([len (unsafe-vector-length vec)]
            [stop* (if stop stop len)])
-      (check-ranges who vec start stop* step len)
+      (check-ranges who type-name vec start stop* step len)
       (values vec start stop* step)))
 
   (define-syntax define-in-vector-like
@@ -1105,7 +1105,7 @@
   (define-sequence-syntax *in-bytes
     (lambda () #'in-bytes)
     (make-in-vector-like 'in-bytes
-                         "bytes"
+                         "byte string"
                          #'bytes?
                          #'unsafe-bytes-length
                          #'in-bytes
diff --git a/racket/collects/racket/private/path.rkt b/racket/collects/racket/private/path.rkt
index 810b901589..a33dfe3bd2 100644
--- a/racket/collects/racket/private/path.rkt
+++ b/racket/collects/racket/private/path.rkt
@@ -25,21 +25,45 @@
        [(if (path-for-some-system? s)
             (eq? (path-convention-type s) 'windows)
             (eq? (system-type) 'windows))
-        (let ([str (if (string? s) s (bytes->string/locale (path->bytes s)))])
-          (if (regexp-match? #rx"^[\u5C][\u5C][?][\u5C]" str)
-              (if (string? s)
-                  (string->path s)
-                  s)
-              (let ([s (string-locale-downcase str)])
-                (bytes->path 
-                 (string->bytes/locale
-                  (regexp-replace* #rx"/" 
-                                   (if (regexp-match? #rx"[/\u5C][. ]+[/\u5C]*$" s)
-                                       ;; Just "." or ".." in last path element - don't remove
-                                       s
-                                       (regexp-replace* #rx"\u5B .\u5D+([/\u5C]*)$" s "\u005C1"))
-                                   bsbs))
-                 'windows))))]
+        (let ([bstr (if (string? s) #f (path->bytes s))])
+          (cond
+            [(and (string? s)
+                  (regexp-match? #rx"^[\u5C][\u5C][?][\u5C]" s))
+             (string->path s)]
+            [(and bstr
+                  (regexp-match? #rx#"^[\x5C][\x5C][?][\x5C]" bstr))
+             s]
+            [else
+             ;; There's no guarantee that `bstr` can be encoded, so
+             ;; deal with parts that can be encoded in chunks
+             (let ([norm (lambda (s)
+                           (string-locale-downcase (regexp-replace* #rx"/" s bsbs)))]
+                   [norm-tail (lambda (s)
+                                (if (regexp-match? #rx"[/\u5C][. ]+[/\u5C]*$" s)
+                                    ;; Just "." or ".." in last path element - don't remove
+                                    s
+                                    (regexp-replace* #rx"(?<=\u5B^ ./\u5C\u5D)\u5B .\u5D+([/\u5C]*)$" s "\u005C1")))]
+                   [finish (lambda (bstr) (bytes->path bstr 'windows))])
+               (cond
+                 [(string? s)
+                  (finish (string->bytes/locale (norm (norm-tail s))))]
+                 [else
+                  (let ([c (bytes-open-converter "" "UTF-8")])
+                    (finish
+                     (let loop ([offset 0])
+                       (let-values ([(new-bstr used status) (bytes-convert c bstr offset (bytes-length bstr))])
+                         (let* ([s (bytes->string/locale new-bstr)]
+                                [tail-s (if (eq? status 'complete) (norm-tail s) s)]
+                                [done (string->bytes/locale (norm tail-s))])
+                           (cond
+                             [(eq? status 'complete)
+                              done]
+                             [(eq? status 'aborts)
+                              (bytes-append done (subbytes bstr (+ offset used)))]
+                             [else
+                              (bytes-append done
+                                            (subbytes bstr (+ offset used) (+ offset used 1))
+                                            (loop (+ offset used 1)))]))))))]))]))]
        [(string? s) (string->path s)]
        [else s])))
   
diff --git a/racket/src/cs/schemified/expander.scm b/racket/src/cs/schemified/expander.scm
index 7d74dbb825..6d390f3604 100644
--- a/racket/src/cs/schemified/expander.scm
+++ b/racket/src/cs/schemified/expander.scm
@@ -70,9 +70,10 @@
                 (1/use-user-specific-search-paths
                  use-user-specific-search-paths)))
 (define rx2276 (regexp "^[\\][\\][?][\\]"))
+(define rx2490 (byte-regexp #vu8(94 91 92 93 91 92 93 91 63 93 91 92 93)))
 (define rx2515 (regexp "/"))
 (define rx2283 (regexp "[/\\][. ]+[/\\]*$"))
-(define rx2870 (regexp "[ .]+([/\\]*)$"))
+(define rx2458 (regexp "(?<=[^ ./\\])[ .]+([/\\]*)$"))
 (define rx2566 (regexp "^\\\\\\\\[?]\\\\[a-z]:"))
 (define rx2590 (regexp "^\\\\\\\\[?]\\\\UNC\\\\"))
 (define rx2623 (regexp "^\\\\\\\\"))
@@ -732,35 +733,86 @@
           #f)))))
 (define bsbs (string '#\x5c '#\x5c))
 (define normal-case-path
-  (lambda (s_0)
-    (begin
-      (if (let ((or-part_0 (path-for-some-system? s_0)))
-            (if or-part_0 or-part_0 (path-string? s_0)))
-        (void)
-        (raise-argument-error
-         'normal-path-case
-         "(or/c path-for-some-system? path-string?)"
-         s_0))
-      (if (if (path-for-some-system? s_0)
-            (eq? (path-convention-type s_0) 'windows)
-            (eq? (system-type) 'windows))
-        (let ((str_0
-               (if (string? s_0)
-                 s_0
-                 (bytes->string/locale (path->bytes s_0)))))
-          (if (regexp-match? rx2276 str_0)
-            (if (string? s_0) (string->path s_0) s_0)
-            (let ((s_1 (string-locale-downcase str_0)))
-              (bytes->path
-               (string->bytes/locale
-                (regexp-replace*
-                 rx2515
-                 (if (regexp-match? rx2283 s_1)
-                   s_1
-                   (regexp-replace* rx2870 s_1 "\\1"))
-                 bsbs))
-               'windows))))
-        (if (string? s_0) (string->path s_0) s_0)))))
+  (letrec ((finish_0
+            (|#%name|
+             finish
+             (lambda (bstr_0) (begin (bytes->path bstr_0 'windows)))))
+           (loop_0
+            (|#%name|
+             loop
+             (lambda (bstr_0 c_0 offset_0)
+               (begin
+                 (call-with-values
+                  (lambda ()
+                    (bytes-convert
+                     c_0
+                     bstr_0
+                     offset_0
+                     (unsafe-bytes-length bstr_0)))
+                  (case-lambda
+                   ((new-bstr_0 used_0 status_0)
+                    (let ((done_0
+                           (string->bytes/locale
+                            (norm_0
+                             (norm-tail_0
+                              (bytes->string/locale new-bstr_0))))))
+                      (if (eq? status_0 'complete)
+                        done_0
+                        (if (eq? status_0 'aborts)
+                          (bytes-append
+                           done_0
+                           (subbytes bstr_0 (+ offset_0 used_0)))
+                          (let ((app_0
+                                 (let ((app_0 (+ offset_0 used_0)))
+                                   (subbytes
+                                    bstr_0
+                                    app_0
+                                    (+ offset_0 used_0 1)))))
+                            (bytes-append
+                             done_0
+                             app_0
+                             (loop_0 bstr_0 c_0 (+ offset_0 used_0 1))))))))
+                   (args (raise-binding-result-arity-error 3 args))))))))
+           (norm-tail_0
+            (|#%name|
+             norm-tail
+             (lambda (s_0)
+               (begin
+                 (if (regexp-match? rx2283 s_0)
+                   s_0
+                   (regexp-replace* rx2458 s_0 "\\1"))))))
+           (norm_0
+            (|#%name|
+             norm
+             (lambda (s_0)
+               (begin
+                 (string-locale-downcase
+                  (regexp-replace* rx2515 s_0 bsbs)))))))
+    (lambda (s_0)
+      (begin
+        (if (let ((or-part_0 (path-for-some-system? s_0)))
+              (if or-part_0 or-part_0 (path-string? s_0)))
+          (void)
+          (raise-argument-error
+           'normal-path-case
+           "(or/c path-for-some-system? path-string?)"
+           s_0))
+        (if (if (path-for-some-system? s_0)
+              (eq? (path-convention-type s_0) 'windows)
+              (eq? (system-type) 'windows))
+          (let ((bstr_0 (if (string? s_0) #f (path->bytes s_0))))
+            (if (if (string? s_0) (regexp-match? rx2276 s_0) #f)
+              (string->path s_0)
+              (if (if bstr_0 (regexp-match? rx2490 bstr_0) #f)
+                s_0
+                (if (string? s_0)
+                  (let ((bstr_1
+                         (string->bytes/locale (norm_0 (norm-tail_0 s_0)))))
+                    (begin (bytes->path bstr_1 'windows)))
+                  (let ((c_0 (bytes-open-converter "" "UTF-8")))
+                    (let ((bstr_1 (loop_0 bstr_0 c_0 0)))
+                      (begin (bytes->path bstr_1 'windows))))))))
+          (if (string? s_0) (string->path s_0) s_0))))))
 (define check-extension-call
   (lambda (s_0 sfx_0 who_0 sep_0 trust-sep?_0)
     (begin
@@ -2930,7 +2982,7 @@
       (void)
       (raise-argument-error 'in-hash-values "hash?" ht_0))))
 (define check-ranges
-  (lambda (who_0 vec_0 start_0 stop_0 step_0 len_0)
+  (lambda (who_0 type-name_0 vec_0 start_0 stop_0 step_0 len_0)
     (begin
       (if (if (exact-nonnegative-integer? start_0)
             (let ((or-part_0 (< start_0 len_0)))
@@ -2939,7 +2991,7 @@
         (void)
         (raise-range-error
          who_0
-         "vector"
+         type-name_0
          "starting "
          start_0
          vec_0
@@ -2949,7 +3001,14 @@
             (if (<= -1 stop_0) (<= stop_0 len_0) #f)
             #f)
         (void)
-        (raise-range-error who_0 "vector" "stopping " stop_0 vec_0 -1 len_0))
+        (raise-range-error
+         who_0
+         type-name_0
+         "stopping "
+         stop_0
+         vec_0
+         -1
+         len_0))
       (if (if (exact-integer? step_0) (not (zero? step_0)) #f)
         (void)
         (raise-argument-error
@@ -2994,7 +3053,7 @@
       (let ((len_0 (|#%app| unsafe-vector-length_0 vec_0)))
         (let ((stop*_0 (if stop_0 stop_0 len_0)))
           (begin
-            (check-ranges who_0 vec_0 start_0 stop*_0 step_0 len_0)
+            (check-ranges who_0 type-name_0 vec_0 start_0 stop*_0 step_0 len_0)
             (values vec_0 start_0 stop*_0 step_0)))))))
 (define check-vector
   (lambda (v_0)
@@ -19314,7 +19373,7 @@
 (define 1/make-set!-transformer
   (let ((struct:set!-transformer_0
          (make-record-type-descriptor* 'set!-transformer #f #f #f #f 1 1)))
-    (let ((effect2444
+    (let ((effect2455
            (struct-type-install-properties!
             struct:set!-transformer_0
             'set!-transformer
@@ -19367,7 +19426,7 @@
                             s
                             'set!-transformer
                             'proc)))))))
-                (let ((effect2446
+                (let ((effect2457
                        (begin
                          (register-struct-constructor! set!-transformer1_0)
                          (register-struct-predicate! set!-transformer?_1)
diff --git a/racket/src/cs/schemified/io.scm b/racket/src/cs/schemified/io.scm
index 06dfe85bad..4eea9444ab 100644
--- a/racket/src/cs/schemified/io.scm
+++ b/racket/src/cs/schemified/io.scm
@@ -2255,7 +2255,7 @@
       (void)
       (raise-argument-error 'in-hash-keys "hash?" ht_0))))
 (define check-ranges
-  (lambda (who_0 vec_0 start_0 stop_0 step_0 len_0)
+  (lambda (who_0 type-name_0 vec_0 start_0 stop_0 step_0 len_0)
     (begin
       (if (if (exact-nonnegative-integer? start_0)
             (let ((or-part_0 (< start_0 len_0)))
@@ -2264,7 +2264,7 @@
         (void)
         (raise-range-error
          who_0
-         "vector"
+         type-name_0
          "starting "
          start_0
          vec_0
@@ -2274,7 +2274,14 @@
             (if (<= -1 stop_0) (<= stop_0 len_0) #f)
             #f)
         (void)
-        (raise-range-error who_0 "vector" "stopping " stop_0 vec_0 -1 len_0))
+        (raise-range-error
+         who_0
+         type-name_0
+         "stopping "
+         stop_0
+         vec_0
+         -1
+         len_0))
       (if (if (exact-integer? step_0) (not (zero? step_0)) #f)
         (void)
         (raise-argument-error
@@ -2319,7 +2326,7 @@
       (let ((len_0 (|#%app| unsafe-vector-length_0 vec_0)))
         (let ((stop*_0 (if stop_0 stop_0 len_0)))
           (begin
-            (check-ranges who_0 vec_0 start_0 stop*_0 step_0 len_0)
+            (check-ranges who_0 type-name_0 vec_0 start_0 stop*_0 step_0 len_0)
             (values vec_0 start_0 stop*_0 step_0)))))))
 (define check-vector
   (lambda (v_0)
@@ -11269,7 +11276,7 @@
             (lambda ()
               (normalise-inputs
                'in-bytes
-               "bytes"
+               "byte string"
                procz1
                procz2
                src-bstr630_0
@@ -18509,7 +18516,7 @@
                                                                   (lambda ()
                                                                     (normalise-inputs
                                                                      'in-bytes
-                                                                     "bytes"
+                                                                     "byte string"
                                                                      procz1
                                                                      procz2
                                                                      (unsafe-unbox*
@@ -18974,7 +18981,7 @@
                                                                         (lambda ()
                                                                           (normalise-inputs
                                                                            'in-bytes
-                                                                           "bytes"
+                                                                           "byte string"
                                                                            procz1
                                                                            procz2
                                                                            bstr9_0
@@ -22688,7 +22695,7 @@
          (if (is-path? p_0)
            (void)
            (raise-argument-error 'path->string "path?" p_0))
-         (1/bytes->string/locale (|#%app| path-bytes p_0) '#\x3f))))))
+         (1/bytes->string/locale (|#%app| path-bytes p_0) '#\xfffd))))))
 (define print-named
   (lambda (what_0 v_0 mode_0 o_0 max-length_0)
     (let ((name_0 (object-name v_0)))
@@ -24827,7 +24834,7 @@
        (lambda ()
          (normalise-inputs
           'in-bytes
-          "bytes"
+          "byte string"
           procz1
           procz2
           bstr_0
@@ -24865,7 +24872,7 @@
        (lambda ()
          (normalise-inputs
           'in-bytes
-          "bytes"
+          "byte string"
           procz1
           procz2
           bstr_0
@@ -25853,7 +25860,7 @@
                        (lambda ()
                          (normalise-inputs
                           'in-bytes
-                          "bytes"
+                          "byte string"
                           procz1
                           procz2
                           bstr5_0
@@ -32175,7 +32182,7 @@
                              (lambda ()
                                (normalise-inputs
                                 'in-bytes
-                                "bytes"
+                                "byte string"
                                 procz1
                                 procz2
                                 bstr_0
@@ -32521,39 +32528,43 @@
     (lambda (bstr_0)
       (let ((len_0 (unsafe-bytes-length bstr_0)))
         (let ((surrogate-count_0
-               (call-with-values
-                (lambda ()
-                  (normalise-inputs
-                   'in-bytes
-                   "bytes"
-                   procz1
-                   procz2
-                   bstr_0
-                   (if big-endian? 0 1)
-                   len_0
-                   2))
-                (case-lambda
-                 ((v*_0 start*_0 stop*_0 step*_0)
-                  (begin
-                    #t
-                    (letrec*
-                     ((for-loop_0
-                       (|#%name|
-                        for-loop
-                        (lambda (n_0 idx_0)
-                          (begin
-                            (if (< idx_0 stop*_0)
-                              (let ((b_0 (unsafe-bytes-ref v*_0 idx_0)))
-                                (let ((n_1
-                                       (let ((n_1
-                                              (if (= (bitwise-and b_0 220) 216)
-                                                (add1 n_0)
-                                                n_0)))
-                                         (values n_1))))
-                                  (for-loop_0 n_1 (+ idx_0 2))))
-                              n_0))))))
-                     (for-loop_0 0 start*_0))))
-                 (args (raise-binding-result-arity-error 4 args))))))
+               (if (= len_0 0)
+                 0
+                 (call-with-values
+                  (lambda ()
+                    (normalise-inputs
+                     'in-bytes
+                     "byte string"
+                     procz1
+                     procz2
+                     bstr_0
+                     (if big-endian? 0 1)
+                     len_0
+                     2))
+                  (case-lambda
+                   ((v*_0 start*_0 stop*_0 step*_0)
+                    (begin
+                      #t
+                      (letrec*
+                       ((for-loop_0
+                         (|#%name|
+                          for-loop
+                          (lambda (n_0 idx_0)
+                            (begin
+                              (if (< idx_0 stop*_0)
+                                (let ((b_0 (unsafe-bytes-ref v*_0 idx_0)))
+                                  (let ((n_1
+                                         (let ((n_1
+                                                (if (=
+                                                     (bitwise-and b_0 220)
+                                                     216)
+                                                  (add1 n_0)
+                                                  n_0)))
+                                           (values n_1))))
+                                    (for-loop_0 n_1 (+ idx_0 2))))
+                                n_0))))))
+                       (for-loop_0 0 start*_0))))
+                   (args (raise-binding-result-arity-error 4 args)))))))
           (let ((str_0
                  (make-string
                   (- (arithmetic-shift len_0 -1) surrogate-count_0))))
diff --git a/racket/src/cs/schemified/regexp.scm b/racket/src/cs/schemified/regexp.scm
index 517f948839..7605675bfd 100644
--- a/racket/src/cs/schemified/regexp.scm
+++ b/racket/src/cs/schemified/regexp.scm
@@ -410,7 +410,7 @@
       (void)
       (raise-argument-error 'in-hash-keys "hash?" ht_0))))
 (define check-ranges
-  (lambda (who_0 vec_0 start_0 stop_0 step_0 len_0)
+  (lambda (who_0 type-name_0 vec_0 start_0 stop_0 step_0 len_0)
     (begin
       (if (if (exact-nonnegative-integer? start_0)
             (let ((or-part_0 (< start_0 len_0)))
@@ -419,7 +419,7 @@
         (void)
         (raise-range-error
          who_0
-         "vector"
+         type-name_0
          "starting "
          start_0
          vec_0
@@ -429,7 +429,14 @@
             (if (<= -1 stop_0) (<= stop_0 len_0) #f)
             #f)
         (void)
-        (raise-range-error who_0 "vector" "stopping " stop_0 vec_0 -1 len_0))
+        (raise-range-error
+         who_0
+         type-name_0
+         "stopping "
+         stop_0
+         vec_0
+         -1
+         len_0))
       (if (if (exact-integer? step_0) (not (zero? step_0)) #f)
         (void)
         (raise-argument-error
@@ -474,7 +481,7 @@
       (let ((len_0 (|#%app| unsafe-vector-length_0 vec_0)))
         (let ((stop*_0 (if stop_0 stop_0 len_0)))
           (begin
-            (check-ranges who_0 vec_0 start_0 stop*_0 step_0 len_0)
+            (check-ranges who_0 type-name_0 vec_0 start_0 stop*_0 step_0 len_0)
             (values vec_0 start_0 stop*_0 step_0)))))))
 (define check-vector
   (lambda (v_0)
@@ -4554,7 +4561,15 @@
     (lambda (bstr_0 i_0)
       (call-with-values
        (lambda ()
-         (normalise-inputs 'in-bytes "bytes" procz1 procz2 bstr_0 i_0 #f 1))
+         (normalise-inputs
+          'in-bytes
+          "byte string"
+          procz1
+          procz2
+          bstr_0
+          i_0
+          #f
+          1))
        (case-lambda
         ((v*_0 start*_0 stop*_0 step*_0)
          (begin
@@ -5541,7 +5556,7 @@
                  (lambda ()
                    (normalise-inputs
                     'in-bytes
-                    "bytes"
+                    "byte string"
                     procz1
                     procz2
                     bstr_0
@@ -5554,7 +5569,7 @@
                     (lambda ()
                       (normalise-inputs
                        'in-bytes
-                       "bytes"
+                       "byte string"
                        procz3
                        procz4
                        s_0
@@ -5610,7 +5625,7 @@
                (lambda ()
                  (normalise-inputs
                   'in-bytes
-                  "bytes"
+                  "byte string"
                   procz5
                   procz6
                   bstr_0
@@ -5690,7 +5705,7 @@
                  (lambda ()
                    (normalise-inputs
                     'in-bytes
-                    "bytes"
+                    "byte string"
                     procz1
                     procz2
                     bstr_0
@@ -5703,7 +5718,7 @@
                     (lambda ()
                       (normalise-inputs
                        'in-bytes
-                       "bytes"
+                       "byte string"
                        procz3
                        procz4
                        s_0
@@ -5759,7 +5774,7 @@
                (lambda ()
                  (normalise-inputs
                   'in-bytes
-                  "bytes"
+                  "byte string"
                   procz5
                   procz6
                   bstr_0
@@ -5844,7 +5859,7 @@
                                   (lambda ()
                                     (normalise-inputs
                                      'in-bytes
-                                     "bytes"
+                                     "byte string"
                                      procz1
                                      procz2
                                      bstr_0
@@ -5857,7 +5872,7 @@
                                      (lambda ()
                                        (normalise-inputs
                                         'in-bytes
-                                        "bytes"
+                                        "byte string"
                                         procz3
                                         procz4
                                         s_0
@@ -5966,7 +5981,7 @@
                                     (lambda ()
                                       (normalise-inputs
                                        'in-bytes
-                                       "bytes"
+                                       "byte string"
                                        procz5
                                        procz6
                                        bstr_0
@@ -6744,7 +6759,7 @@
                             (let ((app_0 (car p_0)))
                               (normalise-inputs
                                'in-bytes
-                               "bytes"
+                               "byte string"
                                procz1
                                procz2
                                s_0
@@ -6757,7 +6772,7 @@
                              (lambda ()
                                (normalise-inputs
                                 'in-bytes
-                                "bytes"
+                                "byte string"
                                 procz3
                                 procz4
                                 s_0
@@ -6899,7 +6914,7 @@
                             (let ((app_0 (car p_0)))
                               (normalise-inputs
                                'in-bytes
-                               "bytes"
+                               "byte string"
                                procz1
                                procz2
                                s_0
@@ -6912,7 +6927,7 @@
                              (lambda ()
                                (normalise-inputs
                                 'in-bytes
-                                "bytes"
+                                "byte string"
                                 procz3
                                 procz4
                                 s_0
@@ -8466,7 +8481,7 @@
                  (lambda ()
                    (normalise-inputs
                     'in-bytes
-                    "bytes"
+                    "byte string"
                     procz1
                     procz2
                     in_0
@@ -8519,7 +8534,7 @@
                                                (lambda ()
                                                  (normalise-inputs
                                                   'in-bytes
-                                                  "bytes"
+                                                  "byte string"
                                                   procz3
                                                   procz4
                                                   in_0
@@ -8535,7 +8550,7 @@
                                                   (lambda ()
                                                     (normalise-inputs
                                                      'in-bytes
-                                                     "bytes"
+                                                     "byte string"
                                                      procz5
                                                      procz6
                                                      must-string_0
diff --git a/racket/src/cs/schemified/schemify.scm b/racket/src/cs/schemified/schemify.scm
index eaf56ba7cd..82f79d4d00 100644
--- a/racket/src/cs/schemified/schemify.scm
+++ b/racket/src/cs/schemified/schemify.scm
@@ -1869,7 +1869,7 @@
       (void)
       (raise-argument-error 'in-hash-values "hash?" ht_0))))
 (define check-ranges
-  (lambda (who_0 vec_0 start_0 stop_0 step_0 len_0)
+  (lambda (who_0 type-name_0 vec_0 start_0 stop_0 step_0 len_0)
     (begin
       (if (if (exact-nonnegative-integer? start_0)
             (let ((or-part_0 (< start_0 len_0)))
@@ -1878,7 +1878,7 @@
         (void)
         (raise-range-error
          who_0
-         "vector"
+         type-name_0
          "starting "
          start_0
          vec_0
@@ -1888,7 +1888,14 @@
             (if (<= -1 stop_0) (<= stop_0 len_0) #f)
             #f)
         (void)
-        (raise-range-error who_0 "vector" "stopping " stop_0 vec_0 -1 len_0))
+        (raise-range-error
+         who_0
+         type-name_0
+         "stopping "
+         stop_0
+         vec_0
+         -1
+         len_0))
       (if (if (exact-integer? step_0) (not (zero? step_0)) #f)
         (void)
         (raise-argument-error
@@ -1933,7 +1940,7 @@
       (let ((len_0 (|#%app| unsafe-vector-length_0 vec_0)))
         (let ((stop*_0 (if stop_0 stop_0 len_0)))
           (begin
-            (check-ranges who_0 vec_0 start_0 stop*_0 step_0 len_0)
+            (check-ranges who_0 type-name_0 vec_0 start_0 stop*_0 step_0 len_0)
             (values vec_0 start_0 stop*_0 step_0)))))))
 (define check-vector
   (lambda (v_0)
diff --git a/racket/src/cs/schemified/thread.scm b/racket/src/cs/schemified/thread.scm
index 8ca8ca7160..893947f256 100644
--- a/racket/src/cs/schemified/thread.scm
+++ b/racket/src/cs/schemified/thread.scm
@@ -582,7 +582,7 @@
       (void)
       (raise-argument-error 'in-hash-keys "hash?" ht_0))))
 (define check-ranges
-  (lambda (who_0 vec_0 start_0 stop_0 step_0 len_0)
+  (lambda (who_0 type-name_0 vec_0 start_0 stop_0 step_0 len_0)
     (begin
       (if (if (exact-nonnegative-integer? start_0)
             (let ((or-part_0 (< start_0 len_0)))
@@ -591,7 +591,7 @@
         (void)
         (raise-range-error
          who_0
-         "vector"
+         type-name_0
          "starting "
          start_0
          vec_0
@@ -601,7 +601,14 @@
             (if (<= -1 stop_0) (<= stop_0 len_0) #f)
             #f)
         (void)
-        (raise-range-error who_0 "vector" "stopping " stop_0 vec_0 -1 len_0))
+        (raise-range-error
+         who_0
+         type-name_0
+         "stopping "
+         stop_0
+         vec_0
+         -1
+         len_0))
       (if (if (exact-integer? step_0) (not (zero? step_0)) #f)
         (void)
         (raise-argument-error
@@ -646,7 +653,7 @@
       (let ((len_0 (|#%app| unsafe-vector-length_0 vec_0)))
         (let ((stop*_0 (if stop_0 stop_0 len_0)))
           (begin
-            (check-ranges who_0 vec_0 start_0 stop*_0 step_0 len_0)
+            (check-ranges who_0 type-name_0 vec_0 start_0 stop*_0 step_0 len_0)
             (values vec_0 start_0 stop*_0 step_0)))))))
 (define check-vector
   (lambda (v_0)
diff --git a/racket/src/io/path/string.rkt b/racket/src/io/path/string.rkt
index e6e41f5514..4e7735992f 100644
--- a/racket/src/io/path/string.rkt
+++ b/racket/src/io/path/string.rkt
@@ -14,4 +14,4 @@
 
 (define/who (path->string p)
   (check who is-path? #:contract "path?" p)
-  (bytes->string/locale (path-bytes p) #\?))
+  (bytes->string/locale (path-bytes p) #\uFFFD))
diff --git a/racket/src/io/string/utf-16-decode.rkt b/racket/src/io/string/utf-16-decode.rkt
index f9cd2c8302..da9af1dd70 100644
--- a/racket/src/io/string/utf-16-decode.rkt
+++ b/racket/src/io/string/utf-16-decode.rkt
@@ -8,10 +8,12 @@
 (define (utf-16-decode bstr)
   (define len (bytes-length bstr))
   (define surrogate-count
-    (for/fold ([n 0]) ([b (in-bytes bstr (if big-endian? 0 1) len 2)])
-      (if (= (bitwise-and b #xDC) #xD8)
-          (add1 n)
-          n)))
+    (if (= len 0)
+        0
+        (for/fold ([n 0]) ([b (in-bytes bstr (if big-endian? 0 1) len 2)])
+          (if (= (bitwise-and b #xDC) #xD8)
+              (add1 n)
+              n))))
   (define str (make-string (- (arithmetic-shift len -1) surrogate-count)))
   (let loop ([i 0] [pos 0])
     (unless (= i len)