Issue
If you have set trusted host patterns by yourself manually in your settings.php to override the Acquia default settings, you might face the error message The provided host name is not valid for this server if you forgot to add the domain you are accessing to in the list of trusted host patterns.
Resolution
By default, the trusted host pattern ($settings['trusted_host_patterns']) is populated with your existing domains registered in the Domains tab in the Acquia Cloud UI, relative to the environment you are looking at. To resolve this, either add the domain to the trusted host pattern or switch back to the default.