The problem has been resolved. The issue was related to the environment. The PostgreSQL user did not have sufficient permissions to access the installation directory of Python.
When I was installing the Windows version of PostgreSQL 18.2.1, I executed the command "CREATE EXTENSION plpython3u;". Error message [2026-02-26 23:35:02] [58P01] Error: Unable to load library "D:/postgresql/PostgreSQL/18/lib/plpython3.dll": The specified module could not be found. [2026-02-26 23:35:02] At location: SQL statement "CREATE FUNCTION plpython3_call_handler() RETURNS language_handler" [2026-02-26 23:35:02] LANGUAGE c AS '$libdir/plpython3'" [2026-02-26 23:35:02] Extension script file "plpython3u--1.0.sql", near line 3 When I placed the python313.dll file in the installation directory of Python 3.13 under the C:\Windows\System32 directory, and executed the command "CREATE EXTENSION plpython3u;" Success, but when creating the Python custom function, an error occurred. [2026-02-26 23:45:01] An I/O error occurred while sending to the backend. [2026-02-26 23:45:01] Received an irrecoverable error. The connection has been damaged.
