diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d014bb5738..8e2a2c5d73 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -3504,12 +3504,7 @@ local0.*    /var/log/postgresql
             </row>
             <row>
              <entry><literal>%u</literal></entry>
-             <entry>Login user name</entry>
-             <entry>yes</entry>
-            </row>
-            <row>
-             <entry><literal>%U</literal></entry>
-             <entry>Current user name</entry>
+             <entry>User name</entry>
              <entry>yes</entry>
             </row>
             <row>
diff --git a/src/backend/utils/error/elog.c b/src/backend/utils/error/elog.c
index 49d9236767..a1a449f2dd 100644
--- a/src/backend/utils/error/elog.c
+++ b/src/backend/utils/error/elog.c
@@ -1826,16 +1826,6 @@ log_line_prefix(StringInfo buf, ErrorData *edata)
 					appendStringInfoString(buf, username);
 				}
 				break;
-			case 'U':
-				if (MyProcPort)
-				{
-					const char *username = GetUserNameFromId(GetUserId());
-
-					if (username == NULL || *username == '\0')
-						username = _("[unknown]");
-					appendStringInfoString(buf, username);
-				}
-				break;
 			case 'd':
 				if (MyProcPort)
 				{