Dear all, I'm facing a problem with psprintf and the %jd format string. I used the following C-code: PG_RETURN_CSTRING(psprintf("%d@%jd", (int)1, (intmax_t)2)); While this worked fine in past, I recently get (with PostgreSQL 13): ERROR: vsnprintf failed: Invalid argument with format string "%d@%jd" I was not able to figure out what's the problem. Apparently this error is thrown when vsnprintf(buf, len, fmt, args) in src/common/psprintf.c returns a negative value. However, calling snprintf(buf, len, "%d@%jd", (int)1, (intmax_t)2)) in a separate test program works fine on my system. I found a workaround. The following call works fine: PG_RETURN_CSTRING(psprintf("%d@%lld", (int)1, (long long)2)); I could live with the workaround, but it is a bit scary, as I don't really understand why "%jd" fails while "%lld" does not. Does anyone know why, and/or is it possible for anyone else to reproduce the problem? Kind regards, Jan Behrens