Slim Application Error

The application could not run because of the following error:

Details

Type: InvalidArgumentException
Message: Slim\Http\Stream::attach argument must be a valid PHP resource
File: /vendor/slim/slim/Slim/Http/Stream.php
Line: 149

Trace

#0 /vendor/slim/slim/Slim/Http/Stream.php(98): Slim\Http\Stream->attach(false)
#1 /app/controller/Page.php(198): Slim\Http\Stream->__construct(false)
#2 [internal function]: Controller\Page->download_source_preview(Object(Slim\Http\Request), Object(Slim\Http\Response), Array)
#3 /vendor/slim/slim/Slim/Handlers/Strategies/RequestResponse.php(41): call_user_func(Array, Object(Slim\Http\Request), Object(Slim\Http\Response), Array)
#4 /vendor/slim/slim/Slim/Route.php(344): Slim\Handlers\Strategies\RequestResponse->__invoke(Array, Object(Slim\Http\Request), Object(Slim\Http\Response), Array)
#5 /vendor/slim/slim/Slim/MiddlewareAwareTrait.php(122): Slim\Route->__invoke(Object(Slim\Http\Request), Object(Slim\Http\Response))
#6 /vendor/slim/slim/Slim/Route.php(316): Slim\Route->callMiddlewareStack(Object(Slim\Http\Request), Object(Slim\Http\Response))
#7 /vendor/slim/slim/Slim/App.php(476): Slim\Route->run(Object(Slim\Http\Request), Object(Slim\Http\Response))
#8 /vendor/slim/slim/Slim/MiddlewareAwareTrait.php(122): Slim\App->__invoke(Object(Slim\Http\Request), Object(Slim\Http\Response))
#9 /vendor/slim/slim/Slim/App.php(370): Slim\App->callMiddlewareStack(Object(Slim\Http\Request), Object(Slim\Http\Response))
#10 /vendor/slim/slim/Slim/App.php(295): Slim\App->process(Object(Slim\Http\Request), Object(Slim\Http\Response))
#11 /index.php(24): Slim\App->run()
#12 {main}