diff --git a/doc/go1.16.html b/doc/go1.16.html
index 0c1fe5b381..ffdbc97c62 100644
--- a/doc/go1.16.html
+++ b/doc/go1.16.html
@@ -454,12 +454,6 @@ Do not send CLs removing the interior tags from such phrases.
 
 <dl id="encoding/json"><dt><a href="/pkg/encoding/json/">encoding/json</a></dt>
   <dd>
-    <p><!-- CL 263619 -->
-      The error message for
-      <a href="/pkg/encoding/json/#SyntaxError">SyntaxError</a>
-      now begins with "json: ", matching the other errors in the package.
-    </p>
-
     <p><!-- CL 234818 -->
       TODO: <a href="https://golang.org/cl/234818">https://golang.org/cl/234818</a>: allow semicolon in field key / struct tag
     </p>
diff --git a/src/cmd/go/testdata/script/mod_proxy_invalid.txt b/src/cmd/go/testdata/script/mod_proxy_invalid.txt
index b9418b4df1..6427cc1527 100644
--- a/src/cmd/go/testdata/script/mod_proxy_invalid.txt
+++ b/src/cmd/go/testdata/script/mod_proxy_invalid.txt
@@ -2,7 +2,7 @@ env GO111MODULE=on
 env GOPROXY=$GOPROXY/invalid
 
 ! go list -m rsc.io/quote@latest
-stderr '^go list -m: module rsc.io/quote: invalid response from proxy "'$GOPROXY'": json: invalid character ''i'' looking for beginning of value$'
+stderr '^go list -m: module rsc.io/quote: invalid response from proxy "'$GOPROXY'": invalid character ''i'' looking for beginning of value$'
 
 ! go list -m rsc.io/quote@1.5.2
-stderr '^go list -m: rsc.io/quote@1.5.2: invalid version: invalid response from proxy "'$GOPROXY'": json: invalid character ''i'' looking for beginning of value$'
+stderr '^go list -m: rsc.io/quote@1.5.2: invalid version: invalid response from proxy "'$GOPROXY'": invalid character ''i'' looking for beginning of value$'
diff --git a/src/cmd/go/testdata/script/mod_query_empty.txt b/src/cmd/go/testdata/script/mod_query_empty.txt
index 1f13d7ad69..f8b6e3e97e 100644
--- a/src/cmd/go/testdata/script/mod_query_empty.txt
+++ b/src/cmd/go/testdata/script/mod_query_empty.txt
@@ -40,7 +40,7 @@ env GOPROXY=file:///$WORK/gatekeeper
 chmod 0000 $WORK/gatekeeper/example.com/join/subpkg/@latest
 cp go.mod.orig go.mod
 ! go get -d example.com/join/subpkg
-stderr 'go get: module example.com/join/subpkg: (invalid response from proxy ".+": json: invalid character .+|reading file://.*/gatekeeper/example.com/join/subpkg/@latest: .+)'
+stderr 'go get: module example.com/join/subpkg: (invalid response from proxy ".+": invalid character .+|reading file://.*/gatekeeper/example.com/join/subpkg/@latest: .+)'
 
 -- go.mod.orig --
 module example.com/othermodule
diff --git a/src/encoding/json/scanner.go b/src/encoding/json/scanner.go
index c3f5f6372d..9dc1903e2d 100644
--- a/src/encoding/json/scanner.go
+++ b/src/encoding/json/scanner.go
@@ -47,7 +47,7 @@ type SyntaxError struct {
 	Offset int64  // error occurred after reading Offset bytes
 }
 
-func (e *SyntaxError) Error() string { return "json: " + e.msg }
+func (e *SyntaxError) Error() string { return e.msg }
 
 // A scanner is a JSON scanning state machine.
 // Callers call scan.reset and then pass bytes in one at a time
diff --git a/src/html/template/escape_test.go b/src/html/template/escape_test.go
index b6031ea60a..fbc84a7592 100644
--- a/src/html/template/escape_test.go
+++ b/src/html/template/escape_test.go
@@ -243,7 +243,7 @@ func TestEscape(t *testing.T) {
 		{
 			"badMarshaler",
 			`<button onclick='alert(1/{{.B}}in numbers)'>`,
-			`<button onclick='alert(1/ /* json: error calling MarshalJSON for type *template.badMarshaler: json: invalid character &#39;f&#39; looking for beginning of object key string */null in numbers)'>`,
+			`<button onclick='alert(1/ /* json: error calling MarshalJSON for type *template.badMarshaler: invalid character &#39;f&#39; looking for beginning of object key string */null in numbers)'>`,
 		},
 		{
 			"jsMarshaler",