403 Error when making changes to a widget

Do you have the Manage Site Theme, Manage User Theme and Manage Custom Pages permissions?

Yes I do have all these permissions. I developed the custom page a few months ago. This is the first time I am unable to edit it.

Can you verify nothing changed with your filestorage and that all the correct permissions are set for your filestorage?

Also, is the widget doing anything related to the platform?  Can you share the code in the widget?

Could you please let me know how I would check that?

I just tried saving it again and it worked. I am not sure what the issue was. I didn't make any change.

If you remove that code and replace it with a simple test HTML statement, do you get the 403 error still?