Referenced AMP URL is not an AMP

Overview
I have installed the AMP WordPress plugin per your requirements. However, my reference pages and AMP pages are failing Google’s AMP testing framework. I am consistently getting the error “Referenced AMP URL is not an AMP”. The template is generating a correct AMP version of my post. However, it fails every time I try to test it. This error is preventing my AMP articles from ranking within Google’s index.

I have tried every version of the AMP settings and disabled all my plugins (but TagDiv) and it still fails. I use both Google Search Console and Google’s AMP test to verify results for every scenario. Below you will find additional details about what I have done.

I can provide you with login details to my hosting or WordPress installation if you would like to test it.

Current set up
The latest version of WordPress
Newspaper theme V 10.1

Example URL of the post that references AMP URL failing – https://sportsblogit.com/cfb/its-official-pac-12-football-is-coming-back-november-7th/

Example URL of AMP post that is failing – https://sportsblogit.com/cfb/its-official-pac-12-football-is-coming-back-november-7th/?amp

AMP Setting tested
1) I have tested AMP “transitional” out of the box and it failed.
– Transitional out of the box did generate a working AMP URL. However, it would NOT pass Google’s testing.

1a) I tested AMP “transitional” with Mobile + AMP-enabled
– My posts did generate a working AMP URL. However, it would NOT pass Google’s testing.

1b) I tested AMP “transitional” with Mobile + AMP-enabled with ALL plugins disabled (but TagDiv)
– My posts did generate a working AMP URL. However, it would NOT pass Google’s testing.

2) I have tested AMP “Standard” out of the box and it failed.
– Transitional out of the box did generate a working AMP URL. However, it would NOT pass Google’s testing.

2a) I tested AMP “Standard” with Mobile + AMP-enabled
– My posts did generate a working AMP URL. However, it would NOT pass Google’s testing.

2b) I tested AMP “Standard” with Mobile + AMP-enabled with ALL plugins disabled (but TagDiv)
– My posts did generate a working AMP URL. However, it would NOT pass Google’s testing.

Sorry, I am running version 10.3.6.1 of Newspaper.

Just sent an email with my details. I have all the same settings as you enabled. It isn’t that the AMP URL isn’t working. The problem is that the base (non-amp) URL is throwing up that error. This is preventing indexing.

You can see the error in these screenshots: https://imgur.com/a/d4t3r0P

But you can see it is that same error.

I was able to find a solution to this problem through Google’s support forum. I am coming back to post it here in case someone has the same problem.

I found out that several hosting companies (including HostGator and Bluehost) install a caching plugin that isn’t shown in your plugins. HostGator’s caching plugin is called “Endurance Cache”. You need to remove this plugin or your AMP content will never be indexed by Google. You can’t disable the plugin natively from within your WordPress settings. Therefore you must remove it from the root. This can be easily done through FTP or file manager.

1) Log into your Cpanel and click on Files.
2) Choose your domain/subdomain and click on the WP-Content.
3) Click on the “mu-plugins”.
4) Rename the File “endurance-page-cache.php” to “endurance-page-cache.php.old”
5) Create a blank file there and name it “endurance-page-cache.php”

Once renamed/removed your AMP pages will work perfect!