diff --git a/racket/src/ChezScheme/LOG b/racket/src/ChezScheme/LOG
index 578b69321e..fb55caef59 100644
--- a/racket/src/ChezScheme/LOG
+++ b/racket/src/ChezScheme/LOG
@@ -2129,3 +2129,9 @@
 - proper unicode handling when retrieving error messages from the OS
   on Windows
     windows.c
+- repair collector handling of an ephemerons that refers to a
+  younger object during incremental promotion
+    gc.c, 4.ms
+- added textual-output-port checks for record-writer write argument
+    print.ss,
+    record.ms, root-experr*
diff --git a/racket/src/ChezScheme/mats/record.ms b/racket/src/ChezScheme/mats/record.ms
index 739af5ccc1..e947fda0b0 100644
--- a/racket/src/ChezScheme/mats/record.ms
+++ b/racket/src/ChezScheme/mats/record.ms
@@ -2840,6 +2840,39 @@
 )
 
 (mat record-writer
+  (equal?
+    (with-output-to-string
+      (lambda ()
+        (define-record-type sp (fields lat))
+        (record-writer (type-descriptor sp)
+          (lambda (x p w) (w (sp-lat x) p)))
+        (pretty-print (list (make-sp 'ugh)))))
+    "(ugh)\n")
+  (error? ; 'sp is not an rtd
+    (with-output-to-string
+      (lambda ()
+        (define-record-type sp (fields lat))
+        (record-writer 'sp
+          (lambda (x p w) (w (sp-lat x) p))))))
+  (error? ; "oops" is not a procedure
+    (with-output-to-string
+      (lambda ()
+        (define-record-type sp (fields lat))
+        (record-writer (type-descriptor sp) "oops"))))
+  (error? ; ugh is not a textual output port
+    (with-output-to-string
+      (lambda ()
+        (define-record-type sp (fields lat))
+        (record-writer (type-descriptor sp)
+          (lambda (x p w) (w p (sp-lat x))))
+        (pretty-print (list (make-sp 'ugh))))))
+  (error? ; procedure not a textual output port
+    (with-output-to-string
+      (lambda ()
+        (define-record-type sp (fields lat))
+        (record-writer (type-descriptor sp)
+          (lambda (x p w) (w (sp-lat x) w)))
+        (pretty-print (list (make-sp 'ugh))))))
   (begin
     (define-record $froz (a b) ([c (+ a b)]))
     (define-record $fruz $froz (d))
diff --git a/racket/src/ChezScheme/mats/root-experr-compile-0-f-f-f b/racket/src/ChezScheme/mats/root-experr-compile-0-f-f-f
index 35b7e117cc..16425c86d0 100644
--- a/racket/src/ChezScheme/mats/root-experr-compile-0-f-f-f
+++ b/racket/src/ChezScheme/mats/root-experr-compile-0-f-f-f
@@ -7819,6 +7819,10 @@ record.mo:Expected error in mat foreign-data: "foreign-set!: invalid value 17 fo
 record.mo:Expected error in mat foreign-data: "foreign-set!: invalid value 17 for foreign type single-float".
 record.mo:Expected error in mat foreign-data: "foreign-set!: invalid value 17 for foreign type double".
 record.mo:Expected error in mat foreign-data: "foreign-set!: invalid value 17 for foreign type double-float".
+record.mo:Expected error in mat record-writer: "record-writer: sp is not a record-type descriptor".
+record.mo:Expected error in mat record-writer: "record-writer: "oops" is not a procedure".
+record.mo:Expected error in mat record-writer: "write: ugh is not a textual output port".
+record.mo:Expected error in mat record-writer: "write: #<procedure> is not a textual output port".
 record.mo:Expected error in mat record-equal/hash: "record-type-equal-procedure: 7 is not a record-type descriptor".
 record.mo:Expected error in mat record-equal/hash: "record-type-equal-procedure: 7 is not a record-type descriptor".
 record.mo:Expected error in mat record-equal/hash: "record-type-equal-procedure: 7 is not a procedure or #f".
diff --git a/racket/src/ChezScheme/mats/root-experr-compile-2-f-f-f b/racket/src/ChezScheme/mats/root-experr-compile-2-f-f-f
index 17de8fbe49..9e6a75b73b 100644
--- a/racket/src/ChezScheme/mats/root-experr-compile-2-f-f-f
+++ b/racket/src/ChezScheme/mats/root-experr-compile-2-f-f-f
@@ -7379,6 +7379,10 @@ record.mo:Expected error in mat foreign-data: "foreign-set!: invalid value 17 fo
 record.mo:Expected error in mat foreign-data: "foreign-set!: invalid value 17 for foreign type single-float".
 record.mo:Expected error in mat foreign-data: "foreign-set!: invalid value 17 for foreign type double".
 record.mo:Expected error in mat foreign-data: "foreign-set!: invalid value 17 for foreign type double-float".
+record.mo:Expected error in mat record-writer: "record-writer: sp is not a record-type descriptor".
+record.mo:Expected error in mat record-writer: "record-writer: "oops" is not a procedure".
+record.mo:Expected error in mat record-writer: "write: ugh is not a textual output port".
+record.mo:Expected error in mat record-writer: "write: #<procedure> is not a textual output port".
 record.mo:Expected error in mat record-equal/hash: "record-type-equal-procedure: 7 is not a record-type descriptor".
 record.mo:Expected error in mat record-equal/hash: "record-type-equal-procedure: 7 is not a record-type descriptor".
 record.mo:Expected error in mat record-equal/hash: "record-type-equal-procedure: 7 is not a procedure or #f".
diff --git a/racket/src/ChezScheme/s/print.ss b/racket/src/ChezScheme/s/print.ss
index 1c20fad73d..06085866f3 100644
--- a/racket/src/ChezScheme/s/print.ss
+++ b/racket/src/ChezScheme/s/print.ss
@@ -173,7 +173,9 @@
                  [(and ($record? x) (not (eq? x #!base-rtd)))
                   (when (print-record)
                     ((record-writer ($record-type-descriptor x)) x (bit-sink)
-                     (lambda (x p) ; could check for p == (bit-sink)
+                     (lambda (x p)
+                       (unless (and (output-port? p) (textual-port? p))
+                         ($oops 'write "~s is not a textual output port" p))
                        (find-dupls x (decr lev) len))))]
                  [(box? x) (find-dupls (unbox x) (decr lev) len)]
                  [(eq? x black-hole) (find-dupls x (decr lev) len)])]
@@ -215,7 +217,9 @@
                            (call/cc
                              (lambda (k)
                                ((record-writer ($record-type-descriptor x)) x (bit-sink)
-                                (lambda (x p) ; could check for p == (bit-sink)
+                                (lambda (x p)
+                                  (unless (and (output-port? p) (textual-port? p))
+                                    ($oops 'write "~s is not a textual output port" p))
                                   (if (cyclic? x (fx+ curlev 1) 0)
                                       (k #t))))
                                #f)))))]
@@ -308,7 +312,9 @@
                       (call/cc
                         (lambda (k)
                           ((record-writer ($record-type-descriptor x)) x (bit-sink)
-                           (lambda (x p) ; could check for p == (bit-sink)
+                           (lambda (x p)
+                             (unless (and (output-port? p) (textual-port? p))
+                               ($oops 'write "~s is not a textual output port" p))
                              (if (down x (fx- xlev 1)) (k #t))))
                           #f)))]
                 [(box? x) (down (unbox x) (fx- xlev 1))]
@@ -706,7 +712,9 @@ floating point returns with (1 0 -1 ...).
                (if (limit? lev)
                    (display-string "#[...]" p)
                    ((record-writer ($record-type-descriptor x)) x p
-                    (lambda (x p) ; could check for p == old p
+                    (lambda (x p)
+                      (unless (and (output-port? p) (textual-port? p))
+                        ($oops 'write "~s is not a textual output port" p))
                       (wr x r (decr lev) len d? env p))))
                (let ([rtd ($record-type-descriptor x)])
                  (cond ; keep in sync with default-record-writer