Laminas - Output has been emitted previously

jvu

Hi there,
I'm trying to install Flarum but keep getting this error:

Fatal error: Uncaught Laminas\HttpHandlerRunner\Exception\EmitterException:
Output has been emitted previously; cannot emit response in
/Users/user/Sites/metaforum/vendor/laminas/laminas-httphandlerrunner/src/Exception/EmitterException.php:24

Anyone has experienced this error before?

askvortsov

jvu is there anything above there?

jvu

askvortsov

Sorry for the late reply!

Below are all errors. Some are just warnings from PHP 8.1, I think.

Deprecated: Return type of Flarum\Foundation\Config::offsetExists($offset) should either
be compatible with ArrayAccess::offsetExists(mixed $offset): bool, or the #[\ReturnTypeWillChange]
attribute should be used to temporarily suppress the notice in 
/Users/user/Sites/metaforum/vendor/flarum/core/src/Foundation/Config.php on line 61

Deprecated: Return type of Flarum\Foundation\Config::offsetGet($offset) should either
be compatible with ArrayAccess::offsetGet(mixed $offset): mixed, or the #[\ReturnTypeWillChange]
attribute should be used to temporarily suppress the notice in
/Users/user/Sites/metaforum/vendor/flarum/core/src/Foundation/Config.php on line 56

Deprecated: Return type of Flarum\Foundation\Config::offsetSet($offset, $value) should either
be compatible with ArrayAccess::offsetSet(mixed $offset, mixed $value): void, or the #[\ReturnTypeWillChange] 
attribute should be used to temporarily suppress the notice in
/Users/user/Sites/metaforum/vendor/flarum/core/src/Foundation/Config.php on line 66

Deprecated: Return type of Flarum\Foundation\Config::offsetUnset($offset) should either
be compatible with ArrayAccess::offsetUnset(mixed $offset): void, or the #[\ReturnTypeWillChange]
attribute should be used to temporarily suppress the notice in
/Users/user/Sites/metaforum/vendor/flarum/core/src/Foundation/Config.php on line 71

Fatal error: Uncaught Laminas\HttpHandlerRunner\Exception\EmitterException:
Output has been emitted previously; cannot emit response in
/Users/user/Sites/metaforum/vendor/laminas/laminas-httphandlerrunner/src/Exception/EmitterException.php:24
Stack trace:
#0 /Users/user/Sites/metaforum/vendor/laminas/laminas-httphandlerrunner/src/Emitter/SapiEmitterTrait.php(40):
Laminas\HttpHandlerRunner\Exception\EmitterException::forOutputSent()
#1 /Users/user/Sites/metaforum/vendor/laminas/laminas-httphandlerrunner/src/Emitter/SapiEmitter.php(27): Laminas\HttpHandlerRunner\Emitter\SapiEmitter->assertNoPreviousOutput()
#2 /Users/user/Sites/metaforum/vendor/laminas/laminas-httphandlerrunner/src/RequestHandlerRunner.php(98): Laminas\HttpHandlerRunner\Emitter\SapiEmitter->emit(Object(Laminas\Diactoros\Response\HtmlResponse))
#3 /Users/user/Sites/metaforum/vendor/flarum/core/src/Http/Server.php(44): Laminas\HttpHandlerRunner\RequestHandlerRunner->run()
#4 /Users/user/Sites/metaforum/public/index.php(26): Flarum\Http\Server->listen()
#5 {main} thrown in /Users/user/Sites/metaforum/vendor/laminas/laminas-httphandlerrunner/src/Exception/EmitterException.php on line 24

My server: Apache2 + PHP 8.1

jvu

askvortsov

After seeing some members mentioned that it does not work with PHP 8.1, I install PHP 7.4 and get these error:

Fatal error: Composer detected issues in your platform: Your Composer dependencies require a PHP version ">= 8.0.2". You are running 7.4.27. in /Users/user/Sites/forum/vendor/composer/platform_check.php on line 24

After I disabled version check while installing, I got these errors:

Notice: Undefined index: data in /Users/user/Sites/forum/vendor/flarum/core/src/Frontend/Content/CorePayload.php on line 74

Fatal error: Uncaught Laminas\HttpHandlerRunner\Exception\EmitterException: Output has been emitted previously; cannot emit response in /Users/user/Sites/forum/vendor/laminas/laminas-httphandlerrunner/src/Exception/EmitterException.php:24 Stack trace:
#0 /Users/user/Sites/forum/vendor/laminas/laminas-httphandlerrunner/src/Emitter/SapiEmitterTrait.php(40): Laminas\HttpHandlerRunner\Exception\EmitterException::forOutputSent()
#1 /Users/user/Sites/forum/vendor/laminas/laminas-httphandlerrunner/src/Emitter/SapiEmitter.php(27): Laminas\HttpHandlerRunner\Emitter\SapiEmitter->assertNoPreviousOutput()
#2 /Users/user/Sites/forum/vendor/laminas/laminas-httphandlerrunner/src/RequestHandlerRunner.php(98): Laminas\HttpHandlerRunner\Emitter\SapiEmitter->emit(Object(Laminas\Diactoros\Response\HtmlResponse))
#3 /Users/user/Sites/forum/vendor/flarum/core/src/Http/Server.php(44): Laminas\HttpHandlerRunner\RequestHandlerRunner->run()
#4 /Users/user/Sites/forum/public/index.php(26): Flarum\Http\Server->listen()
#5 {main} thrown in /Users/user/Sites/forum/vendor/laminas/laminas-httphandlerrunner/src/Exception/EmitterException.php on line 24

And this is the log: https://pastebin.com/1ucw4csN

Something is wrong with type hinting of the Symfony Filesystem module.

jvu

OK, I installed PHP 8.0.15 and everything seems to be fine now.

clarkwinkelmann

You can hide PHP's Notice and Deprecated messages by editing your php.ini configuration. You can set display_errors to Off to tell PHP to stop displaying those errors in the page.

Flarum will then be able to continue the boot process.

pepoliveras

Hey folks, just to say that it worked for me hiding PHP's Notice and Deprecated messages.

Remember instead of editing your php.ini configuration you can also set display_errors to Off (to tell PHP to stop displaying those errors in the page) by pasting the following code in a PHP file (for example index.php):

display_errors(false);

Thank you for your help!

Cheers! 🙂