P0001: raise_exception

What does it mean?

A PL/pgSQL function or trigger deliberately raised an error with RAISE EXCEPTION. This error is produced not by the database engine but by business-rule code written by you (or a library).

Why does it happen?

When the business logic fails a validation, the developer called RAISE EXCEPTION 'message' USING ERRCODE = ...;. For example, a trigger raises a custom error to block a disallowed update or to enforce a consistency rule.

How to fix it

The error message and any HINT/DETAIL fields explain what the function rejected; satisfy the business rule accordingly. To find the source, inspect the relevant function/trigger code (the RAISE statements). If a specific SQLSTATE is needed, assign a meaningful code with RAISE ... USING ERRCODE instead of the generic P0001, so the application can tell it apart.