Issue with Saving FrontPage Template and Regenerating HTML

An issue occurs when I try to save the FrontPage template. Here is the screenshot:

When I try to regenerate the HTML, another issue occurs:

Can you help me figure out this issue?

PS: I checked online the export JSON of the template and the result is ok

Hi @weedor,

For errors like that it is a good idea to check the browser error console and/or network log to see what is happening.

Often is it caused by a server issue, for example it could be caused if the json api is erroring because the server is restricting it for whatever reason (in the past we have had sites on hosted servers that returned 404 or 403 errors).

Or it could be caused by another plugin that may be affecting the stability of your installation.

So I recommend first getting information on exactly what the error is that is causing saving to fail.

Thank you, @StrangeTech, for your reply.
I tested the JSON file that I exported from the entire front page on a test page I created. Everything ran smoothly, so I decided to delete the entire front page and reset it. Everything is running well now, but it was quite a headache.