A hosting firewall or web application firewall, commonly ModSecurity, may reject a settings request—especially when a field contains HTML, JavaScript, an iframe, or an advertising snippet.
- Confirm that you are signed in as an administrator and note the exact page, time, and field that triggers the error.
- Check the web-server and firewall logs, or ask the hosting provider for the rule ID that blocked that request.
- Ask the provider to whitelist the specific false-positive rule for the required request, then save and test again.
Do not disable the firewall for the whole server merely to bypass one rule. If ordinary text-only settings also fail, check file permissions, the server error log, and whether the request is reaching AdLinkFly before assuming the content filter is responsible.