[Neos] Exception after composer update: An invalid node path...

[Simon Schaufelberger (Schaufi)]

im really frustrated about the upgrade process of neos. almost every 
time i try to update my neos after some months im stuck with a problem. 
I think im doing everything right...

basic installation with only one additional package developed by me, the 
rest is a normal demo installation.
here are my update commands:

composer update
./flow doctrine:migrate
./flow flow:core:migrate
./flow flow:cache:flush
./flow cache:warmup

did i forget something?

ok after doing all this, i go to my neos website and login into the 
backend. i get the loginscreen (fine so far!) and after login attempt i 
get the following exception:

Exception while rendering
page<TYPO3.Neos:Page>/body<TYPO3.TypoScript:Template>/footer:
An invalid node path was specified: is of type NULL but a string is 
expected.

here some detailed lines from the exception file in the logs folder:

Uncaught exception #1357832901 in line 611 of 
C:\xampp\htdocs\neos\Data\Temporary\Development\Cache\Code\Flow_Object_Classes\TYPO3_TYPO3CR_Domain_Model_Node.php: 
An invalid node path was specified: is of type NULL but a string is 
expected.

45 TYPO3\TYPO3CR\Domain\Model\NodeData_Original::normalizePath(NULL)
44 TYPO3\TYPO3CR\Domain\Model\Node_Original::getNode(NULL)
43 
TYPO3\Neos\TypoScript\ContentCollectionImplementation_Original::evaluate()
42 
TYPO3\TypoScript\Core\Runtime_Original::evaluateInternal("page<TYPO3.Neos:Page>/body<TYPO3.TypoScript:Template>/footer", 
"NULL", NULL)
41 
TYPO3\TypoScript\Core\Runtime_Original::evaluate("page<TYPO3.Neos:Page>/body<TYPO3.TypoScript:Template>/footer")
40 
TYPO3\TypoScript\TypoScriptObjects\Helpers\TypoScriptPathProxy_Original::objectAccess()
39 
TYPO3\Fluid\Core\Parser\SyntaxTree\ObjectAccessorNode_Original::getPropertyPath(TYPO3\Fluid\Core\ViewHelper\TemplateVariableContainer, 
"footer", TYPO3\Fluid\Core\Rendering\RenderingContext)
38 {closure}()
...
-- 
Regards, Schaufi