when we try to login to piwik site we get the following error
Error: Form security failed. Please reload the form and check that your cookies are enabled. If you use a proxy server, you must configure Piwik to accept the proxy header that forwards the Host header. Also, check that your Referer header is sent correctly.
"Warning: session_write_close() [function.session-write-close]: write failed: No space left on device (28) in /opt/lampp/htdocs/piwik/libs/Zend/Session.php on line 691 "
how to resolve this error
any suggestions please.