[Flow] Adding an interface leads to "Execution of subprocess failed with exit code 255 and no output"

[Christian Eßl]

I can't figure out how to add an interface in TYPO3 Flow. For example I added this very basic interface as "SortableInterface.php" to the Domain/Model/ folder:

--------------------------------------------
<?php
namespace Test\CMS\Domain\Model;

interface SortableInterface {
	
/**
 * @var integer
 */
protected $index;

}
?>
---------------------------------------------

Now if I try to access the page or run ./flow doctrine:update in the shell, I get this error:

#1355480641: Execution of subprocess failed with exit code 255 and no output. The erroneous command was: FLOW_ROOTPATH='/path/to/my/webfolder/' FLOW_CONTEXT='Development' XDEBUG_CONFIG='idekey=FLOW_SUBREQUEST remote_port=9001' "/usr/bin/php" -c '/etc/php5/apache2/php.ini' '/path/to/my/webfolder/Packages/Framework/TYPO3.Flow/Classes/TYPO3/Flow/Core/../../../../Scripts/flow.php' 'typo3.flow:core:compile'

I didn't even implement the interface in any model. - I just added the php file. It looks like the autoloader has a problem with my interface. When I remove the php file from my Domain/Model/-folder everything works fine again.