Cannot create or edit emails or templates in Mosaico

Question

Just migrated a WordPress site to a new server. When we try to create, edit or adjust a template that uses Mosaico we cannot get the following (this is from the edit mosaico templates page and the console shows 404 errors.

We have done the following:

• Checked both directories & resource urls settings. We have also put hte full paths in these settings
• Cleared Cache
• Reinstalled Mosaico & Flexmailer
• Upgraded CiviCRM from 5.28.2 to 5.28.4

It seems Mosaico cannot load the requested

Answer 1

It turns out the issue was being caused by the resource url for the extensions directory. The path was set correctly but the resource url had a typo. The extension directory was not the standard /ext. Once the resource url was corrected and the cache cleared all works fine.