WordPress Core Updates and Version Compatibility

Keeping WordPress core and PHP versions updated is essential for site security and preventing critical plugin compatibility errors.

Based on 8 community reports.

Linked sources: 8.

Known Issues

• PHP version incompatibility
• Plugin conflicts after core updates
• JSON response errors

Community Q&A

Why does my site show a critical error after a WordPress update?

Critical errors often occur due to plugin or theme incompatibility with the new WordPress core or updated PHP versions.

Should I update my PHP version when updating WordPress?

Yes, using an outdated PHP version like 7.3 or 7.4 poses security risks and may cause plugins to fail.

How do I fix the ‘Updating failed. The response is not a valid JSON response’ error?

This error is often caused by server configuration issues, conflicting plugins, or incorrect file permissions.

Reddit Sources

• I’ve been doing WordPress development wrong for 3 years. Here’s what I learned the hard way… (r/Wordpress)
• “Updating failed. The response is not a valid JSON response” (r/Wordpress)
• WordPress front page mysteriously switched to draft – no log entry, any ideas? (r/Wordpress)
• Installing old wordpress site (r/Wordpress)
• Website pentested. Help me fix the vulnerabilities found. (r/Wordpress)
• Question about nested classes in CSS for Wordpress (r/Wordpress)
• Anyone else getting critical error on site from Gmedia Gallery plugin? (r/Wordpress)
• Guide to securing your WordPress site (r/Wordpress)