postgres=# select '$.field ? (@ like_regex "a\\")'::jsonpath; -- does not work ERROR: invalid regular expression: invalid escape \ sequence LINE 1: select '$.field ? (@ like_regex "a\\")'::jsonpath;
It is working just fine. It sees both the regex and the backslash character and then helpfully tells you that the regex you wrote is bogus since the backslash you wrote isn't escaping anything.
If you need a literal backslash in a jsonpath string literal you need to write four of them. Each pair leaves one \ in the regex and then \\ in a regex is just a literally matched character.
