Error Not Acceptable An appropriate representation of the requested resource could not be found on this server.

After transferring the site to another host and trying to save changes in the admin panel, for example, such a code:

<p class="block">
  <svg xmlns="http://www.w3.org/2000/svg" width="700" height="72" viewBox="0 0 700 72">
    <text x="0" y="70">Stroked text</text>
  </svg>
</p>

I get an error:

Not Acceptable An appropriate representation of the requested resource could not be found on this server.

At the same time, it is impossible to edit the posts, you have to reload the page and hope for autosave of your drafts. The problem is that ModSecurity is installed and mod_security is enabled on the side of the hosting provider. The simplest solution is to raise a consult woth the technical support of your hosting provider with this description:

Please disable the mod_security option for my account, because in the WordPress admin panel I get this error Not Acceptable An appropriate representation of the requested resource could not be found on this server.

You can try to write the following rules in your .htaccess, which is located in the root of the site:

<IfModule mod_security.c>
SecFilterEngine Off
SecFilterScanPOST Off
</IfModule>

If it does not help, just write a request to the technical support team.