UmbHost Limtied

This has been solved. There was a stray space at the beginning of the configuration.php file

Sure it's below, as I say the internal API's all work great, it only breaks if I try to access it via the external api

When I try to make an API request (/includes/api.php?action=DomainWhois&responsetype=json) for the whois search I receieve a 500 error. From the error in the log, it looks to be an issue with a vendor library: {main} {"exception [error] [WHMCS Application] ERROR: Laminas\HttpHandlerRunner\Exception\EmitterException: Unable to emit response; headers already sent in /home/wwwroot/vendor/laminas/laminas-httphandlerrunner/src/Exception/EmitterException.php:19 Stack trace: #0 /home/sites/25a/2/27a7ef7eec/my/wwwroot/vendor/laminas/laminas-httphandlerrunner/src/Emitter/SapiEmitterTrait.php(36): Laminas\HttpHandlerRunner\Exception\EmitterException::forHeadersSent() #1 /home/wwwroot/vendor/laminas/laminas-httphandlerrunner/src/Emitter/SapiEmitter.php(27): Laminas\HttpHandlerRunner\Emitter\SapiEmitter->assertNoPreviousOutput() #2 /home/wwwroot/includes/api.php(0): Laminas\HttpHandlerRunner\Emitter\SapiEmitter->emit(Object(WHMCS\Http\Message\JsonResponse)) #3 Interestingly the error only occurs with the external api, if I make an internal api request it works.

Since upgrading to 8.3 I am seeing a spinner in the footer of the homepage: