[TYPO3-mvc] updateAction throw an exception

[Daniel Lorenz]

Hello guys,

I ran into a new problem with extbase and can't find a solution to solve
this.

I have an object and an edit view for this object. When I send the
filled form I see this exception:

#1249479819: The "modified object" is does not have an existing
counterpart in this repository.

Tx_Extbase_Persistence_Exception_UnknownObject thrown in file
/var/www/kompnet/cms/typo3conf/ext/extbase/Classes/Persistence/Repository.php in line 222.

I don't know, why this exception raises.

In my view I have a form like this:

--- begin edit.html ---
<f:form method="post" action="update" name="user" object="{user}">
	<f:form.checkbox property="acceptagb" value="1"/><br />
	...
	<f:form.submit value="Edit" />
</form>
--- end edit.html ---

When I sending the form the firebug shows me, that 

--- begin ---
tx_foobar_pi1[__hmac]          ...
tx_foobar_pi1[__referre...     edit
tx_foobar_pi1[__referre...     User
tx_foobar_pi1[__referre...     Foobar
tx_foobar_pi1[user][__i...     14
tx_foobar_pi1[user][acc...	
tx_foobar_pi1[user][acc...     1
...
--- end ---

The update function looks like this:

--- begin ---
	/**
	 * Updates an existing User and forwards to the index action
afterwards.
	 *
	 * @param Tx_Foobar_Domain_Model_User $user
	 */
	public function updateAction(Tx_Foobar_Domain_Model_User $user) {
		$this->userRepository->update($user);
		$this->flashMessageContainer->add('Your User was updated.');
		$this->redirect('index');
	}
--- end ---

Before calling update($user) I var_dump the $user-getUid(), but this is
NULL.

What do I wrong?

Thanks for any hint.

Daniel