WordPress – REST API 404 error

I installed WordPress 5.3.2 and using the TwentyTwenty theme for this non profit I joined. I was trying to make a new Page and save but it kept complaining the REST API call failed and the page would not save.

The REST API call gave the following unexpected result: (404) Not Found The requested URL /wp-json/wp/v2/types/post was not found on this server.

Looked at Tools->Heath Check and noticed that I missed some php lib. After installing the libs that did not fix the error either.

Fix:

You likely changed the Settings -> Permalink

I had changed it to just post. Once I changed it to custom

index.php/%postname%

the API error went away and verified that the heath check passed too.

Resource:

https://wordpress.org/support/topic/url-rewrites-not-working/