diff --git a/src/backend/access/transam/multixact.c b/src/backend/access/transam/multixact.c
index 95a39db545..b553518bab 100644
--- a/src/backend/access/transam/multixact.c
+++ b/src/backend/access/transam/multixact.c
@@ -940,14 +940,18 @@ GetNewMultiXactId(int nmembers, MultiXactOffset *offset)
 			/* complain even if that DB has disappeared */
 			if (oldest_datname)
 				ereport(WARNING,
-						(errmsg("database \"%s\" must be vacuumed before %u more MultiXactIds are used",
+						(errmsg_plural("database \"%s\" must be vacuumed before %u more MultiXactId is used",
+									   "database \"%s\" must be vacuumed before %u more MultiXactIds are used",
+									   multiWrapLimit - result,
 								oldest_datname,
 								multiWrapLimit - result),
 				 errhint("Execute a database-wide VACUUM in that database.\n"
 						 "You might also need to commit or roll back old prepared transactions.")));
 			else
 				ereport(WARNING,
-						(errmsg("database with OID %u must be vacuumed before %u more MultiXactIds are used",
+						(errmsg_plural("database with OID %u must be vacuumed before %u more MultiXactId is used",
+									   "database with OID %u must be vacuumed before %u more MultiXactIds are used",
+									   multiWrapLimit - result,
 								oldest_datoid,
 								multiWrapLimit - result),
 				 errhint("Execute a database-wide VACUUM in that database.\n"
@@ -1982,14 +1986,18 @@ SetMultiXactIdLimit(MultiXactId oldest_datminmxid, Oid oldest_datoid)
 
 		if (oldest_datname)
 			ereport(WARNING,
-					(errmsg("database \"%s\" must be vacuumed before %u more MultiXactIds are used",
+					(errmsg_plural("database \"%s\" must be vacuumed before %u more MultiXactId is used",
+								   "database \"%s\" must be vacuumed before %u more MultiXactIds are used",
+								   multiWrapLimit - curMulti,
 							oldest_datname,
 							multiWrapLimit - curMulti),
 					 errhint("To avoid a database shutdown, execute a database-wide VACUUM in that database.\n"
 							 "You might also need to commit or roll back old prepared transactions.")));
 		else
 			ereport(WARNING,
-					(errmsg("database with OID %u must be vacuumed before %u more MultiXactIds are used",
+					(errmsg_plural("database with OID %u must be vacuumed before %u more MultiXactId is used",
+								   "database with OID %u must be vacuumed before %u more MultiXactIds are used",
+								   multiWrapLimit - curMulti,
 							oldest_datoid,
 							multiWrapLimit - curMulti),
 					 errhint("To avoid a database shutdown, execute a database-wide VACUUM in that database.\n"
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 16bf78d77f..d08b38213b 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -6138,7 +6138,7 @@ StartupXLOG(void)
 		ereport(ERROR,
 				(errcode(ERRCODE_OUT_OF_MEMORY),
 				 errmsg("out of memory"),
-			errdetail("Failed while allocating an XLog reading processor")));
+			errdetail("Failed while allocating an XLog reading processor.")));
 	xlogreader->system_identifier = ControlFile->system_identifier;
 
 	if (read_backup_label(&checkPointLoc, &backupEndRequired,
diff --git a/src/backend/utils/adt/json.c b/src/backend/utils/adt/json.c
index ecfe063762..9f3f5d4feb 100644
--- a/src/backend/utils/adt/json.c
+++ b/src/backend/utils/adt/json.c
@@ -728,7 +728,7 @@ json_lex_string(JsonLexContext *lex)
 							ereport(ERROR,
 							   (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
 								errmsg("invalid input syntax for type json"),
-								errdetail("high order surrogate must not follow a high order surrogate."),
+								errdetail("Unicode high surrogate must not follow a high surrogate."),
 								report_json_context(lex)));
 						hi_surrogate = (ch & 0x3ff) << 10;
 						continue;
@@ -739,7 +739,7 @@ json_lex_string(JsonLexContext *lex)
 							ereport(ERROR,
 							   (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
 								errmsg("invalid input syntax for type json"),
-								errdetail("low order surrogate must follow a high order surrogate."),
+								errdetail("Unicode low surrogate must follow a high surrogate."),
 								report_json_context(lex)));
 						ch = 0x10000 + hi_surrogate + (ch & 0x3ff);
 						hi_surrogate = -1;
@@ -749,7 +749,7 @@ json_lex_string(JsonLexContext *lex)
 						ereport(ERROR,
 								(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
 								 errmsg("invalid input syntax for type json"),
-								 errdetail("low order surrogate must follow a high order surrogate."),
+								 errdetail("Unicode low surrogate must follow a high surrogate."),
 								 report_json_context(lex)));
 
 					/*
@@ -783,7 +783,7 @@ json_lex_string(JsonLexContext *lex)
 						ereport(ERROR,
 								(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
 								 errmsg("invalid input syntax for type json"),
-								 errdetail("Unicode escape for code points higher than U+007F not permitted in non-UTF8 encoding"),
+								 errdetail("Unicode escape values cannot be used for code point values above 007F when the server encoding is not UTF8."),
 								 report_json_context(lex)));
 					}
 
@@ -795,7 +795,7 @@ json_lex_string(JsonLexContext *lex)
 					ereport(ERROR,
 							(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
 							 errmsg("invalid input syntax for type json"),
-							 errdetail("low order surrogate must follow a high order surrogate."),
+							 errdetail("Unicode low surrogate must follow a high surrogate."),
 							 report_json_context(lex)));
 
 				switch (*s)
@@ -856,7 +856,7 @@ json_lex_string(JsonLexContext *lex)
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
 						 errmsg("invalid input syntax for type json"),
-						 errdetail("low order surrogate must follow a high order surrogate."),
+						 errdetail("Unicode low surrogate must follow a high surrogate."),
 						 report_json_context(lex)));
 
 			appendStringInfoChar(lex->strval, *s);
@@ -868,7 +868,7 @@ json_lex_string(JsonLexContext *lex)
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
 				 errmsg("invalid input syntax for type json"),
-		errdetail("low order surrogate must follow a high order surrogate."),
+		errdetail("Unicode low surrogate must follow a high surrogate."),
 				 report_json_context(lex)));
 
 	/* Hooray, we found the end of the string! */
diff --git a/src/backend/utils/adt/jsonfuncs.c b/src/backend/utils/adt/jsonfuncs.c
index 2cbe83200f..bcb9354364 100644
--- a/src/backend/utils/adt/jsonfuncs.c
+++ b/src/backend/utils/adt/jsonfuncs.c
@@ -1239,7 +1239,7 @@ json_populate_record(PG_FUNCTION_ARGS)
 	if (!type_is_rowtype(argtype))
 		ereport(ERROR,
 				(errcode(ERRCODE_DATATYPE_MISMATCH),
-				 errmsg("first argument must be a rowtype")));
+				 errmsg("first argument of json_populate_record must be a row type")));
 
 	if (PG_ARGISNULL(0))
 	{
@@ -1581,7 +1581,7 @@ json_populate_recordset(PG_FUNCTION_ARGS)
 	if (!type_is_rowtype(argtype))
 		ereport(ERROR,
 				(errcode(ERRCODE_DATATYPE_MISMATCH),
-				 errmsg("first argument must be a rowtype")));
+				 errmsg("first argument of json_populate_recordset must be a row type")));
 
 	rsi = (ReturnSetInfo *) fcinfo->resultinfo;
 
diff --git a/src/test/regress/expected/json.out b/src/test/regress/expected/json.out
index e5da9956bc..1a357988e4 100644
--- a/src/test/regress/expected/json.out
+++ b/src/test/regress/expected/json.out
@@ -929,19 +929,19 @@ select json '{ "a":  "\ud83d\ude04\ud83d\udc36" }' -> 'a' as correct_in_utf8;
 
 select json '{ "a":  "\ud83d\ud83d" }' -> 'a'; -- 2 high surrogates in a row
 ERROR:  invalid input syntax for type json
-DETAIL:  high order surrogate must not follow a high order surrogate.
+DETAIL:  Unicode high surrogate must not follow a high surrogate.
 CONTEXT:  JSON data, line 1: { "a":...
 select json '{ "a":  "\ude04\ud83d" }' -> 'a'; -- surrogates in wrong order
 ERROR:  invalid input syntax for type json
-DETAIL:  low order surrogate must follow a high order surrogate.
+DETAIL:  Unicode low surrogate must follow a high surrogate.
 CONTEXT:  JSON data, line 1: { "a":...
 select json '{ "a":  "\ud83dX" }' -> 'a'; -- orphan high surrogate
 ERROR:  invalid input syntax for type json
-DETAIL:  low order surrogate must follow a high order surrogate.
+DETAIL:  Unicode low surrogate must follow a high surrogate.
 CONTEXT:  JSON data, line 1: { "a":...
 select json '{ "a":  "\ude04X" }' -> 'a'; -- orphan low surrogate
 ERROR:  invalid input syntax for type json
-DETAIL:  low order surrogate must follow a high order surrogate.
+DETAIL:  Unicode low surrogate must follow a high surrogate.
 CONTEXT:  JSON data, line 1: { "a":...
 --handling of simple unicode escapes
 select json '{ "a":  "the Copyright \u00a9 sign" }' ->> 'a' as correct_in_utf8;
diff --git a/src/test/regress/expected/json_1.out b/src/test/regress/expected/json_1.out
index 641f3458c7..201fcb2d20 100644
--- a/src/test/regress/expected/json_1.out
+++ b/src/test/regress/expected/json_1.out
@@ -923,28 +923,28 @@ ERROR:  cannot call json_populate_recordset on a nested object
 -- handling of unicode surrogate pairs
 select json '{ "a":  "\ud83d\ude04\ud83d\udc36" }' -> 'a' as correct_in_utf8;
 ERROR:  invalid input syntax for type json
-DETAIL:  Unicode escape for code points higher than U+007F not permitted in non-UTF8 encoding
+DETAIL:  Unicode escape values cannot be used for code point values above 007F when the server encoding is not UTF8.
 CONTEXT:  JSON data, line 1: { "a":...
 select json '{ "a":  "\ud83d\ud83d" }' -> 'a'; -- 2 high surrogates in a row
 ERROR:  invalid input syntax for type json
-DETAIL:  high order surrogate must not follow a high order surrogate.
+DETAIL:  Unicode high surrogate must not follow a high surrogate.
 CONTEXT:  JSON data, line 1: { "a":...
 select json '{ "a":  "\ude04\ud83d" }' -> 'a'; -- surrogates in wrong order
 ERROR:  invalid input syntax for type json
-DETAIL:  low order surrogate must follow a high order surrogate.
+DETAIL:  Unicode low surrogate must follow a high surrogate.
 CONTEXT:  JSON data, line 1: { "a":...
 select json '{ "a":  "\ud83dX" }' -> 'a'; -- orphan high surrogate
 ERROR:  invalid input syntax for type json
-DETAIL:  low order surrogate must follow a high order surrogate.
+DETAIL:  Unicode low surrogate must follow a high surrogate.
 CONTEXT:  JSON data, line 1: { "a":...
 select json '{ "a":  "\ude04X" }' -> 'a'; -- orphan low surrogate
 ERROR:  invalid input syntax for type json
-DETAIL:  low order surrogate must follow a high order surrogate.
+DETAIL:  Unicode low surrogate must follow a high surrogate.
 CONTEXT:  JSON data, line 1: { "a":...
 --handling of simple unicode escapes
 select json '{ "a":  "the Copyright \u00a9 sign" }' ->> 'a' as correct_in_utf8;
 ERROR:  invalid input syntax for type json
-DETAIL:  Unicode escape for code points higher than U+007F not permitted in non-UTF8 encoding
+DETAIL:  Unicode escape values cannot be used for code point values above 007F when the server encoding is not UTF8.
 CONTEXT:  JSON data, line 1: { "a":...
 select json '{ "a":  "dollar \u0024 character" }' ->> 'a' as correct_everywhere;
  correct_everywhere