Roundup: Solutions for WordPress 5.0 Upgrade Causing 500 Server Errors

2018, Dec 29    

After updating my WordPress blog to 5.0 everything looked like it was working, until I went to add a new post, then I got the internal server error. My issue turned out to be a plugin that was not compatible with the new Gutenberg editor.

In this roundup, I’m going to list the solutions people are trying from easy to hard. Starting with permalinks.

Try re-saving your permalinks settings to see if that solves your problem. Apparently the .htaccess files are not saving correctly due to some third party WordPress installers trying to do the upgrade.

Solution #2 – Install The Classic Editor

I’m seeing numerous amounts of people who installed the classic editor plugin and that fixed their problem. You can find it here.

Solution #3 – Temporarily Disable Any Security Plugins

I’ve seen a few people saying this worked, not sure what security plugins are causing issues with 5.0, but I will update the post a soon someone gives more details.

I believe the problem comes from security plugins blocking the wp-json requests which the new Gutenberg editor uses. The rules will typically be in your .htaccess file.

Solution #4 – Disabled All Plugins

Start disabling plugins one at a time until you find the offending plugin. This process is time consuming, but it worked for me. The plugin causing the problem was HTML Editor Syntax Highlighter version 2.2.6.

Solution #5 – Check System Requirements

Solution #6 – Cloudflare

Not sure how Cloudflare plays into all of this, but some people claim by changing the type of SSL connection between Cloudflare and their blog has resolved the 500 server errors. I don’t recommend this, but I wanted to add it as I’ve come across a few people claiming that it worked.