Laminas Error - Oops! Something went wrong...

[hostblitz]

Got the: Oops! Something went wrong and we couldn't process your request. Please go back to the previous page and try again.

Getting this error after upgrading from 7.9 to 8.02 

Exception: Laminas\HttpHandlerRunner\Exception\EmitterException: Output has been emitted previously; cannot emit response in /public_html/billing/vendor/laminas/laminas-httphandlerrunner/src/Exception/EmitterException.php:24 Stack trace: #0 /public_html/billing/vendor/laminas/laminas-httphandlerrunner/src/Emitter/SapiEmitterTrait.php(40): Laminas\HttpHandlerRunner\Exception\EmitterException::forOutputSent() #1 public_html/billing/vendor/laminas/laminas-httphandlerrunner/src/Emitter/SapiEmitter.php(27): Laminas\HttpHandlerRunner\Emitter\SapiEmitter->assertNoPreviousOutput() #2 /public_html/billing/index.php(0): Laminas\HttpHandlerRunner\Emitter\SapiEmitter->emit(Object(WHMCS\ClientArea)) #3 {main}

When I switch back to a really old template like the six or portal, the error does go away, but not any recent versions. Not really sure what is happening. 

On PHP 7.3, but tried 7.2, 7.1, 7.0... to see if I could get the error to disappear. 

 

 

[WHMCS John]

Hi @hostblitz,

Check for some blank space in an after-market module or hook. This has been observed to cause this error:

 

[hostblitz]

Thank you. That was it, a small space in the header template file of the theme we were using. I appreciate the direction.