diff -U3 /home/pavel/src/postgresql.master/src/test/regress/expected/json_jsonpath.out /home/pavel/src/postgresql.master/src/test/regress/results/json_jsonpath.out
--- /home/pavel/src/postgresql.master/src/test/regress/expected/json_jsonpath.out	2020-03-06 09:07:33.433585004 +0100
+++ /home/pavel/src/postgresql.master/src/test/regress/results/json_jsonpath.out	2020-03-06 09:13:50.700635746 +0100
@@ -1449,8 +1449,8 @@
 select json_path_query('{}', '$.datetime()');
 ERROR:  jsonpath item method .datetime() can only be applied to a string
 select json_path_query('""', '$.datetime()');
-ERROR:  datetime format is not unrecognized
-HINT:  use datetime template argument for explicit format specification
+ERROR:  datetime format is not recognized: ""
+HINT:  Use a datetime template argument to specify the input data format.
 select json_path_query('"12:34"', '$.datetime("aaa")');
 ERROR:  invalid datetime format separator: "a"
 select json_path_query('"aaaa"', '$.datetime("HH24")');