What was the order in which you made these configurations initially?
Did you install and configure:
* Translatepress first
* The payment processor second?
If so, it’s possible this issue was happening even without having TranslatePress installed. And due to some of the changes we’re doing inside WordPress to better work with URL’s and make multilingual possible it actually fixes this?
The one function I can think of that might cause this is that we’re filtering home_url. We don’t touch site_url.
Try to go to translatepress-multilingual/class-translate-press.php and comment out this line:
$this->loader->add_filter( ‘home_url’, $this->url_converter, ‘add_language_to_home_url’, 1, 4 );
Then see if the error is appearing. If it is, it should narrow down the issue.
Another thing to check is to connect to your database using something like PhpMyAdmin and see what’s inside wp_options -> site_url and home_url.
The ones you see in the WordPress -> General Settings page can be filtered and incorrect.
Finally, clear and disable all and every caching you have. I see you have cloudflair in front if I’m not mistaken. Disable all caching in cloudflair temporarely when investigating this issue.
And please ask for support from FastPay, having TranslatePress disabled causing it to fail sounds like something they should be able to investigate properly and see WHY reconfiguring the plugin is causing it to fail as this is not an issue of TranslatePress.