[TYPO3] error when trying to update reference index

[Andreas Balzer]

Hi!
I use TYPO3 4.0 and get the following error, when i try to update my 
reference index trough the BE:

Warning: array_unique() [function.array-unique]: The argument should be 
an array in 
/home/ess-erfurt/www/htdocs/t3lib/class.t3lib_flexformtools.php on line 150

Warning: Invalid argument supplied for foreach() in 
/home/ess-erfurt/www/htdocs/t3lib/class.t3lib_flexformtools.php on line 166

What can i do? Is there a patch?

Andreas