How to fix Assert failure in PostgreSQL

PostgreSQLADVANCEDCRITICALUpdated Dec 28, 2025· 172 views

Assert failures indicate internal consistency check violations in PostgreSQL, typically caused by data corruption, software bugs, or hardware issues. Check server logs, update PostgreSQL, and isolate the cause by testing extensions and hardware.

Quick fix

Fixes Assert failure

tail -100 /var/log/postgresql/postgresql-*.log
# Or check the data directory
tail -100 /path/to/pgdata/log/postgresql-*.log
  1. Check PostgreSQL server logs for the full error message
  2. Update PostgreSQL to the latest minor version
  3. Disable extensions one by one to isolate the cause
  4. Run hardware diagnostics
postgresql — error
tail -100 /var/log/postgresql/postgresql-*.log
# Or check the data directory
tail -100 /path/to/pgdata/log/postgresql-*.log
Assert failure

What this error means

An assert failure in PostgreSQL signals that the database engine detected an internal consistency check violation. This occurs when the database encounters a condition that should never happen under normal operation. Assert failures can originate from two sources: the PL/pgSQL ASSERT statement used in stored procedures for debugging purposes, or internal PostgreSQL consistency checks that fail due to unexpected engine states. When an internal consistency check fails, it indicates a serious problem such as memory corruption, a bug in PostgreSQL or an extension, data corruption in tables or indexes, or a hardware fault. In production builds, assertions are typically disabled; if you encounter this error in production, you may be running a debug build or experiencing a critical system fault.

Typical symptoms

  • PostgreSQL server crashes or terminates unexpectedly
  • Queries fail with "Assert failure" message in logs
  • Server logs contain SIGABRT signal or core dump
  • Specific operations (INSERT, UPDATE, DELETE) consistently fail
  • Custom PL/pgSQL functions raise assert_failure exceptions
  • Database becomes unresponsive or enters abnormal state

Common causes

  1. Memory corruption from hardware defects or kernel issues
  2. Bugs in PostgreSQL itself or installed extensions
  3. Corrupted table, index, or system catalog data
  4. Incompatible or poorly-written third-party extensions
  5. Running a debug build of PostgreSQL in production
  6. Database files damaged by filesystem or storage layer errors

How to fix "Assert failure"

1Check PostgreSQL server logs for the full error message

Look at the PostgreSQL log file to find the complete assert failure message and stack trace. This provides crucial context about where the failure occurred.

bash
tail -100 /var/log/postgresql/postgresql-*.log
# Or check the data directory
tail -100 /path/to/pgdata/log/postgresql-*.log

Note the exact assertion that failed, the function name, and line number.

2Update PostgreSQL to the latest minor version

Assert failures may be caused by bugs fixed in newer minor versions. Update to the latest stable release in your major version branch.

bash
# On Ubuntu/Debian
sudo apt-get update
sudo apt-get upgrade postgresql-14  # Replace 14 with your version

# Then restart PostgreSQL
sudo systemctl restart postgresql

Always test updates on a non-production environment first.

3Disable extensions one by one to isolate the cause

Third-party extensions can cause assert failures. Test if the issue persists without extensions.

sql
-- List installed extensions
SELECT * FROM pg_extension;

-- Disable extensions one at a time
DROP EXTENSION IF EXISTS extension_name CASCADE;

-- After dropping, run the operation that caused the failure

If the error disappears after disabling an extension, that extension is the culprit. Update or replace it.

4Run hardware diagnostics

Memory corruption and disk errors are common causes of assert failures. Run hardware tests to rule them out.

bash
# Test RAM using memtest86+
boot into memtest86+
# Let it run for at least 8+ hours

# Check disk health
sudo smartctl -a /dev/sda  # Replace with your disk

# Check system logs for hardware errors
sudo dmesg | grep -i error

If hardware issues are found, contact your infrastructure provider or hardware vendor.

5Verify database integrity if hardware is healthy

If hardware is fine but assert failures continue, check for data corruption.

bash
# Stop PostgreSQL
sudo systemctl stop postgresql

# Run pg_filedump to inspect table structures (careful with production)
pg_filedump /path/to/pgdata/base/your_database_oid/table_oid

# Restart and consider reindexing
sudo systemctl start postgresql
sql
-- Reindex problematic tables
REINDEX TABLE table_name;

-- Analyze to update statistics
ANALYZE table_name;
6Report reproducible assert failures to the PostgreSQL project

If you can reliably reproduce the assert failure and suspect a PostgreSQL bug, report it to the PostgreSQL mailing list.

1. Gather information:
 - PostgreSQL version: SELECT version();
 - Operating system and version
 - Complete error message and stack trace from logs
 - Steps to reproduce

2. Post to pgsql-bugs@postgresql.org with clear details

3. PostgreSQL developers may request a core dump or additional debugging information to help fix the issue.

Advanced notes

Assert failures in PL/pgSQL user code (using the ASSERT statement) are different from internal consistency check failures. User-code assert failures are debug aids and can be disabled by setting plpgsql.check_asserts to OFF in postgresql.conf. Internal assert failures, however, indicate a serious problem requiring immediate investigation. In PostgreSQL source code, assertions are often disabled in production builds (#ifndef USE_ASSERT_CHECKING) to improve performance. If you encounter internal assert failures in a production build, you may actually be running a debug build. Some assert failures related to replication, transactions, or specific operations may indicate race conditions or edge cases in certain PostgreSQL versions. Always have backups before attempting recovery steps.

Frequently asked questions

What does "Assert failure" mean?
An assert failure in PostgreSQL signals that the database engine detected an internal consistency check violation. This occurs when the database encounters a condition that should never happen under normal operation. Assert failures can originate from two sources: the PL/pgSQL ASSERT statement used in stored procedures for debugging purposes, or internal PostgreSQL consistency checks that fail due to unexpected engine states.
How do I fix "Assert failure"?
Assert failures indicate internal consistency check violations in PostgreSQL, typically caused by data corruption, software bugs, or hardware issues. Check server logs, update PostgreSQL, and isolate the cause by testing extensions and hardware.
What causes "Assert failure"?
Memory corruption from hardware defects or kernel issues Bugs in PostgreSQL itself or installed extensions Corrupted table, index, or system catalog data
Is the "Assert failure" error serious?
Yes. This is a critical-severity error that usually blocks work until it is fixed, but the steps above resolve it.

Official resources & further reading