The response is not a valid JSON response

Thanks for reaching out. This came up previously, with the cause being WAF rules:
https://www.ads-software.com/support/topic/error-the-response-is-not-a-valid-json-response-7/

If you haven’t added any Analytics snippet and the issue remains while using a Chromium based browser please try and activate the Health Check & Troubleshooting Plugin before following the steps below:

1. Activate “Troubleshooting mode” (This will temporary deactivate all third party plugins and switch to a core theme for you only, as a logged in user)
2. Activate the AMP plugin while in troubleshooting mode
3. Try to once again enable the “Mobile Redirection” option

If you find the issue no longer occurs there may be a plugin conflict or configuration resulting in this issue. If so you can try enabling other plugins one by one while in troubleshooting mode, checking for the same issue each time. You can also try enabling your active WordPress theme to check for any theme feature or function which may be impacting AMP mobile redirection settings.

Feel free to share any findings here, or alternatively share your Site Health information privately using this form and we can see if we’re able to identify anything which may be resulting in such behavior.

I followed your instruction and it don’t works, still error. Maybe server’s firewall? Site isn’t used by Cloudflare.

Sorry to hear that didn’t work, checking your servers Firewall might indeed be a good troubleshooting next step. If the same error appears please share your Site Health information privately using this form we can check your setup.

With the form or here please also share the following:

1. Does the same error appear when using the Chrome browser?
2. Are you able to make other AMP configurations changes successfully, such as switching modes?

The form has sent. Switching modes comes with error too. I contact my hosting about this.

Thanks for sharing. I notice you’re using Elementor which isn’t fully AMP compatible, along with LiteSpeed Cache which may have some configurations which could cause issues for your AMP URLs. Regardless troubleshooting mode which you’ve already attempted should have made these redundant when checking.

While you’re testing hosting configurations or Firewall settings can you share whether you’ve notice any issues non specific to the AMP plugin, such as publishing a new post?

I got answer from hosting support:

“Hello,

Could you please let me know the steps to recreate the problem from our end and please let us know the IP address as well so that we can check further with our server firewall.”

Do AMP plugin serve IP address?

Support got a temporary account by me and she could enable it without issue. She’s still looking for the root cause of the issue.

That’s good to know it’s working on another site. Do you encounter this same notice when saving a new post using the default editor and not Elementor?

It’s not Elementor-related issue. It’s conflict with Hide My WP plugin. Reinstall WP and install AMP and Elementor without any issues.

Nice troubleshooting, thanks for providing an update. I’ve tested the Hide My WP Ghost Plugin, can you confirm this is the one you used? I didn’t encounter the same issue with default configuration.

It’s no Hide My WP Ghost I used, it’s Hide My Hide from Codecanyon.

Interesting! Many thanks for the update. And best of luck with your site, if you have any queries be sure to get in touch.

If you have a moment free please share your plugin feedback, we’d love to hear how you’re finding the various dashboards and product integration.