Understand the symptom.
Decide without making it worse.

Pharma spam usually combines generated pages, cloaking and persistence. Clean the generator and index footprint, not only visible text.

A persistent object-cache drop-in can break every request when Redis is unavailable or misconfigured. Confirm the drop-in and failover behaviour.

A checksum mismatch means a core file differs from the official release or an unexpected file exists. Preserve evidence before replacing it.

A repeated database-update screen means WordPress does not see the expected schema version after the upgrade request. Check code/database pairing and writes.

WordPress found a directory with the package’s target name. Decide whether it is an incomplete install, an old copy or a different component before deleting it.

This login error often comes from URL, HTTPS, cache or early-output problems rather than the browser blocking all cookies.

The database reached its connection limit or cannot release connections fast enough. Measure active sessions and slow work before raising the ceiling.

A crashed-table message identifies storage-engine damage or an unclean shutdown. Back up first and confirm the affected table and engine.

A class-not-found fatal means the expected PHP class was not loaded. Trace namespace, autoloader and deployed files.

The code called a function that was never loaded in that request. Identify the caller, expected provider and load order.

Headers already sent means PHP produced output before WordPress tried to send cookies, redirects or HTTP headers. The first-output file and line are the clue.

Permission denied names a file operation the PHP user could not perform. Check owner, group, ACL and mount mode before changing numbers.