TYPO3 Core

With TYPO3 6.12 (not with the versions before) I allways get a PHP warning in some backend modules (e.g. Extension Manager, Install Tool...) and in the frontend:

#1: PHP Warning: preg_match(): Compilation failed: internal error: previously-checked referenced subpattern not found at offset 1963 in /pathto/typo3_src-6.2.12/typo3/sysext/fluid/Classes/Core/Parser/TemplateParser.php line 813

That is this line:

if (preg_match(self::$SCAN_PATTERN_SHORTHANDSYNTAX_OBJECTACCESSORS, $section, $matchedVariables) > 0) {

When I set SYS['displayErrors'] = 0, I get this Message:

Oops, an error occurred!

This exception should never be thrown, there is most likely some error in the regular expressions. Please post your template to the bugtracker at forge.typo3.org.

When I set FE['debug'] = FALSE, I get this error:

#1237900529: The argument "triggers" was registered with type "array", but is of type "string" in view helper "TYPO3\CMS\Extensionmanager\ViewHelpers\Be\TriggerViewHelper" 

Or here antoher example:

Oops, an error occurred!

The argument "arguments" was registered with type "array", but is of type "string" in view helper "TYPO3\CMS\Fluid\ViewHelpers\RenderViewHelper"