Initial assessment
WordPress Error Cases

Error establishing a Redis connection

“Error establishing a Redis connection” in WordPress: causes and what to check

Updated 2026-10-31
# Common log entries
PHP Fatal error:  Uncaught Error: Class "Redis" not found in …/wp-content/object-cache.php

The object-cache.php file in wp-content sends cache reads and writes to Redis. When Redis cannot be reached, or the PHP Redis extension is missing, WordPress cannot load and shows this message or a fatal error.

Which of these matches what you see?

object-cache.php came along with the files, and the new host has no Redis server or uses a different address.

The Redis process stopped, or restarted with a new password, so connections fail.

Deleting the plugin folder leaves wp-content/object-cache.php in place, and WordPress keeps loading it.

Common causes

Leftover drop-in: object-cache.php remains after the caching plugin was removed.
Redis unreachable: The host, port, or password is wrong, or Redis is not running.
Missing PHP extension: The PHP Redis extension is not installed for the current PHP version.
Redis memory limit: Redis rejects writes when it reaches its memory limit.

References

  1. Cache (Advanced Administration Handbook)

What the system does

Errors caused by stale cache files or a lost object-cache backend are handled automatically: the system removes the stuck cache files and, when the cache backend is unreachable, removes the leftover configuration. Fixes are made on a copy of your site in the recovery station and written back only after re-verification passes. In your site’s database, the protected tables (members, comments, orders and form submissions) are copied as structure only. In SSH and FTP mode, the system creates a pre-recovery backup on your host before writing back and restores from it if verification after write-back fails. If the recovery cannot be completed, the recovery fee is refunded in full.

  1. Initial assessment: Enter the site URL
  2. Copy to the recovery station: Work runs on the copy
  3. Find the cause: Item-by-item checks
  4. Recover and re-check: Home and inner pages
  5. Write back or deliver: Only after re-checks pass

Use WP119 when the site does not load and you cannot reach wp-content over FTP or SSH.

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