php7 - Custom SessionHandler raises session_write_close() warning - php

Question

I upgraded my project from php5.6 to php7.0 and got from time to time a php warning about session_write_close(), showing me the correct path to my temp folder.
My project uses a custom database session handler which worked perfectly with the older php version.
The error is as follows:
Warning: Unknown: Failed to write session data (user). Please verify
that the current setting of session.save_path is correct (C:\my\path)
in Unknown on line 0
Here is my write() fucntion:
/**
* #param string $id
* #param string $data
* #return bool
* #throws Zend_Db_Adapter_Exception
*/
public function write($id, $data)
{
$dateTime = date('Y-m-d H:i:s');
$newDateTime = date('Y-m-d H:i:s', strtotime($dateTime . sprintf(' + %s seconds', $this->getMaxLifetime())));
$sessionValues = array("id" => $id, "expires_at" => $newDateTime, "session_data" => $data);
$sel = new Zend_Db_Select($this->_zdb);
$sel->from(self::TABLE_NAME, array('id'))
->where('id = ?', $id);
$sessionExists = (bool)$this->_zdb->fetchOne($sel);
if($sessionExists) {
$result = $this->_zdb->update(self::TABLE_NAME, $sessionValues, array('id = ?' => $id));
} else {
$result = $this->_zdb->insert(self::TABLE_NAME, $sessionValues);
}
if($result) {
return true;
} else {
return false;
}
}
Any ideas what I can do about it?

Answer 1

Ok, finally I found the solution:
My database adapter inside my custom session handler returns 0 on an update on the session table which doesn't update any values.
I returned the result of my query in the write()-function.
This guy here explained the problem.
The SessionHandlerInterface::write() function raises this warning in case it returns false.
Maybe this helps somebody else as well.