A database corruption (PostgreSQL) has occurred.
👉 Specifically, a part of the data file (block) is corrupted and cannot be read by the database.
Cause
unexpected server shutdown
disk / hardware issue
error during data write
Resolution
Recommended approach:
restore the database from a backup
Possible fix (advanced):
procedures for repairing the database exist:
https://stackoverflow.com/questions/5220344/postgresql-invalid-page-header-in-block
👉 these interventions are risky and may result in data loss