Internal server error while trying to update

Hi, I tried to update my piwik from the orange message in the top right corner of the dashboard and it broke. Then I restore it with a back up I had on my server and tried to update again and it happened again. Can you tell me what to do so I can update safely? Thank you, Ana

-----This is the message that appeared:

Internal Server Error

The server encountered an internal error or misconfiguration and was unable
to complete your request.

Please contact the server administrator,
and inform them of the time the error occurred, and anything you might have
done that may have caused the error.

More information about this error may be available in the server error log.

Additionally, a 404 Not Found error was encountered while trying to use an
ErrorDocument to handle the request.

-----And when I tried to enter my piwik after that, this was what I found:

Fatal error: Call to undefined method Piwik\Updater::addComponentToCheck() in
on line 130

Fatal error: Uncaught exception ‘Zend_Session_Exception’ with message
’Session must be started before any output has been sent to the browser;
output started in
in /home/buenasuerte3/
Stack trace: #0
Zend_Session::start(true) #1
Zend_Session_Namespace->__construct(‘CorePluginsAdmi…’, false) #2
Piwik\Session\SessionNamespace->_construct(‘CorePluginsAdmi…’) #3
Piwik\Nonce::getNonce(‘CorePluginsAdmi…’) #4 [internal function]:
Piwik\Plugins\CorePluginsAdmin\Controller->safemode(Array) #5
in /home/buenasuerte3/
on line 443