PostgreSQL raises error code P0004 (assert_failure) when an internal ASSERT statement fails during execution, indicating a serious logic fault in server code or an extension.
PostgreSQL Error P0004 assert_failure signals that an internal ASSERT test in the server or an extension failed. Reproduce in a test environment, upgrade to a patched PostgreSQL version, disable problematic extensions, and report the bug to the PostgreSQL community to resolve the fault.
PostgreSQL Error P0004
PostgreSQL error P0004, condition name assert_failure, appears when an internal ASSERT statement fails while the server executes C code. The failure halts the query and returns the error immediately.
The ASSERT macro exists only in builds compiled with assertions enabled, so production binaries rarely show this message.
Seeing it in production signals either a custom build or an extension compiled with assertions.
The error fires when PostgreSQL or an extension reaches a code path considered impossible by the developer.
The ASSERT guard checks an invariant and aborts if false.
Typical triggers include corrupted system catalogs, invalid tuple headers, out-of-range values, or misuse of server programming interfaces by C extensions.
First, reproduce the crash in a staging copy. Collect stack traces with gdb or llvm-gdb to locate the failing source line.
Identify whether core PostgreSQL or a third-party module owns the frame.
If the frame belongs to PostgreSQL core, upgrade to the latest minor release because maintainers quickly patch assertion bugs. If it belongs to an extension, update or disable that extension and retest.
Upgrading from 14.2 to 14.10 removed a known assert_failure inside heapam when HOT pruning met a corrupted index.
Applying the patch fixed production crashes.
Users of custom C functions often trigger assertions by returning Datum values with wrong typmod. Recompiling the function with correct PG_RETURN macros eliminated the error.
Always run production with official PostgreSQL binaries compiled without assertions.
Test new extensions in a staging environment that has assertions enabled to catch bugs early.
Leverage Galaxy’s version-controlled SQL collections to share vetted queries instead of ad-hoc C code, reducing the need for risky server-side programming.
Error XX000 internal error resembles assert_failure but appears in non-assert builds. Treat it the same way: upgrade and report.
Error 57P03 cannot_connect_now may follow assert_failure if the crash forces a restart. Investigate the original assert_failure first.
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Distributions built with --enable-cassert trigger ASSERT failures instead of silently continuing, exposing developer-only checks.
Poorly tested C extensions can violate server invariants and hit ASSERT macros placed in PostgreSQL headers.
Bit-rot in pg_class or index pages may feed invalid states into core code paths guarded by ASSERT.
Loading an extension compiled against a different PostgreSQL version can break ABI expectations and raise assertions.
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Usually not. The error points to a server or extension bug, though certain SQL can trigger the flawed path.
No. Assertions indicate critical logic issues. Upgrade or patch immediately.
Install debug symbols, start PostgreSQL under gdb, set breakpoints on ExceptionalCondition, run the query, then use bt full.
Galaxy prevents most risky code paths by centralizing vetted SQL and limiting the need for custom C functions, reducing assertion exposure.
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