Customizer gives a 404 page

Tried to access the customizer function in wordpress today and it gave me a 404 page. What would cause that?

Hi there,

First of all Test for a plugin conflict by deactivating all third-party plugins. If the issue is resolved, a plugin is likely causing the problem. Identify the problematic plugin by reactivating them one by one.

Let me know how it goes, we can also get someinsight from your server log, if you can provide it here it will help us identify the problem.

I look forward to hearing from you.