diff --git a/NEWS.md b/NEWS.md
index b626d697e3efcf..8478a47caa3637 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -188,8 +188,8 @@ They are still available on rubygems.org and can be installed with
   * 0.8.2 to [v0.9.0][io-console-v0.9.0], [v0.9.1][io-console-v0.9.1], [v0.9.2][io-console-v0.9.2]
 * ipaddr 1.2.9
   * 1.2.8 to [v1.2.9][ipaddr-v1.2.9]
-* json 3.0.0.rc1
-  * 2.18.0 to [v2.18.1][json-v2.18.1], [v2.19.0][json-v2.19.0], [v2.19.1][json-v2.19.1], [v2.19.2][json-v2.19.2], [v2.19.3][json-v2.19.3], [v2.19.4][json-v2.19.4], [v2.19.5][json-v2.19.5], [v2.19.6][json-v2.19.6], [v2.19.7][json-v2.19.7], [v2.19.8][json-v2.19.8], [v2.19.9][json-v2.19.9], [v2.20.0][json-v2.20.0], [v2.21.0][json-v2.21.0], [v2.21.2][json-v2.21.2], [v3.0.0.rc1][json-v3.0.0.rc1]
+* json 3.0.0
+  * 2.18.0 to [v2.18.1][json-v2.18.1], [v2.19.0][json-v2.19.0], [v2.19.1][json-v2.19.1], [v2.19.2][json-v2.19.2], [v2.19.3][json-v2.19.3], [v2.19.4][json-v2.19.4], [v2.19.5][json-v2.19.5], [v2.19.6][json-v2.19.6], [v2.19.7][json-v2.19.7], [v2.19.8][json-v2.19.8], [v2.19.9][json-v2.19.9], [v2.20.0][json-v2.20.0], [v2.21.0][json-v2.21.0], [v2.21.2][json-v2.21.2], [v3.0.0.rc1][json-v3.0.0.rc1], [v3.0.0][json-v3.0.0]
 * net-protocol 0.3.0
   * 0.2.2 to [v0.3.0][net-protocol-v0.3.0]
 * openssl 4.0.2
@@ -442,6 +442,7 @@ A lot of work has gone into making Ractors more stable, performant, and usable.
 [json-v2.21.0]: https://github.com/ruby/json/releases/tag/v2.21.0
 [json-v2.21.2]: https://github.com/ruby/json/releases/tag/v2.21.2
 [json-v3.0.0.rc1]: https://github.com/ruby/json/releases/tag/v3.0.0.rc1
+[json-v3.0.0]: https://github.com/ruby/json/releases/tag/v3.0.0
 [net-protocol-v0.3.0]: https://github.com/ruby/net-protocol/releases/tag/v0.3.0
 [openssl-v4.0.1]: https://github.com/ruby/openssl/releases/tag/v4.0.1
 [openssl-v4.0.2]: https://github.com/ruby/openssl/releases/tag/v4.0.2
diff --git a/common.mk b/common.mk
index 17c1ae45358bc5..7b63cbd96db34a 100644
--- a/common.mk
+++ b/common.mk
@@ -1356,8 +1356,11 @@ clean-build-tool:
 
 $(srcdir)/revision.h$(no_baseruby:no=~disabled~): $(REVISION_H)
 
+REVISION_H_CMD = $(BASERUBY) $(tooldir)/file2lastrev.rb -q --revision.h \
+	--srcdir="$(srcdir)" --output=revision.h --timestamp=$(REVISION_H)
+
 $(REVISION_H)$(no_baseruby:no=~disabled~):
-	$(Q) $(BASERUBY) $(tooldir)/file2lastrev.rb -q --revision.h --srcdir="$(srcdir)" --output=revision.h --timestamp=$@
+	$(Q) $(REVISION_H_CMD)
 $(REVISION_H)$(yes_baseruby:yes=~disabled~):
 	$(Q) exit > $@
 
@@ -1521,6 +1524,11 @@ update-src::
 	$(Q) $(RM) $(REVISION_H) revision.h "$(srcdir)/$(REVISION_H)" "$(srcdir)/revision.h"
 	$(Q) exit > "$(srcdir)/revision.h"
 
+# $(REVISION_H) can have been made already in this run, as a prerequisite
+# of the included dependency file, and make does not make it twice.
+update-src$(no_baseruby:no=~disabled~)::
+	$(Q) $(REVISION_H_CMD)
+
 update-remote:: update-src update-download
 update-download:: $(ALWAYS_UPDATE_UNICODE:yes=update-unicode)
 update-download:: update-gems
diff --git a/ext/json/lib/json/version.rb b/ext/json/lib/json/version.rb
index 8e7e3175533fb1..eb53003aa73232 100644
--- a/ext/json/lib/json/version.rb
+++ b/ext/json/lib/json/version.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module JSON
-  VERSION = '3.0.0.rc1'
+  VERSION = '3.0.0'
 end
diff --git a/ext/json/parser/parser.c b/ext/json/parser/parser.c
index fc6a7bbf62f626..5cba2feb6cdc1e 100644
--- a/ext/json/parser/parser.c
+++ b/ext/json/parser/parser.c
@@ -1041,6 +1041,9 @@ NOINLINE(static) VALUE json_string_unescape(JSON_ParserState *state, JSON_Parser
                         raise_syntax_error_at("incomplete surrogate pair at %s", state, p);
                         break;
                     }
+                } else if ((ch & 0xFC00) == 0xDC00) {
+                    raise_syntax_error_at("unpaired trailing surrogate at %s", state, p);
+                    break;
                 }
 
                 int unescape_len = convert_UTF32_to_UTF8(buffer, ch);
diff --git a/imemo.c b/imemo.c
index 890b4ee9447a4a..8ef12feb7e8de8 100644
--- a/imemo.c
+++ b/imemo.c
@@ -298,7 +298,7 @@ rb_imemo_memsize(VALUE obj)
       case imemo_memo:
         break;
       case imemo_ment:
-        size += sizeof(((rb_method_entry_t *)obj)->def);
+        size += sizeof(struct rb_method_definition_struct);
 
         break;
       case imemo_svar:
diff --git a/test/json/json_minefield_parser_test.rb b/test/json/json_minefield_parser_test.rb
index e6dcb54b8d341b..5558014099f0d8 100644
--- a/test/json/json_minefield_parser_test.rb
+++ b/test/json/json_minefield_parser_test.rb
@@ -22,12 +22,9 @@ def define_test(name, &block)
     i_string_overlong_sequence_2_bytes
     i_string_not_in_unicode_range
     i_string_lone_utf8_continuation_byte
-    i_string_lone_second_surrogate
     i_string_iso_latin_1
     i_string_invalid_utf-8
-    i_string_incomplete_surrogate_pair
     i_string_UTF-8_invalid_sequence
-    i_object_key_lone_2nd_surrogate
   )
 
   COMMENT_TESTS = %w(
@@ -56,6 +53,9 @@ def define_test(name, &block)
     i_string_utf16BE_no_BOM
     i_string_utf16LE_no_BOM
     i_structure_UTF-8_BOM_empty_object
+    i_string_lone_second_surrogate
+    i_string_incomplete_surrogate_pair
+    i_object_key_lone_2nd_surrogate
   )
 
   if RUBY_ENGINE == 'jruby'
diff --git a/test/json/json_parser_test.rb b/test/json/json_parser_test.rb
index 84839585fcc755..3e88442991566b 100644
--- a/test/json/json_parser_test.rb
+++ b/test/json/json_parser_test.rb
@@ -403,6 +403,15 @@ def test_invalid_surogates
     assert_raise(JSON::ParserError) { parse('"\\uD800_________________"') }
     assert_raise(JSON::ParserError) { parse('"\\uD800\\u0041"') }
     assert_raise(JSON::ParserError) { parse('"\\uD800\\u004') }
+    # Lone trailing surrogate (issue #1069): parser previously returned an
+    # invalid-UTF-8 String instead of raising. Symmetric to the leading cases
+    # above.
+    assert_raise(JSON::ParserError) { parse('"\\uDC00"') }
+    assert_raise(JSON::ParserError) { parse('"\\uDC00_________________"') }
+    assert_raise(JSON::ParserError) { parse('"\\uDC00\\uD800"') }
+    # Valid pair still parses to the astral codepoint U+10000.
+    assert_predicate JSON.parse('"\\uD800\\uDC00"'), :valid_encoding?
+    assert_equal "\u{10000}", JSON.parse('"\\uD800\\uDC00"')
   end
 
   def test_parse_big_integers