PHP Warning: session_start()

[Aficionado]

Hello.

Today all my error.log is full of these (5 Osclass sites). Any one knows what it is ?

Osclass 3.5.9, no changes.

Thanks

[28-Jan-2016 02:22:06 America/Indiana/Indianapolis] PHP Warning:  session_start(): The session id is too long or contains illegal characters, valid characters are a-z, A-Z, 0-9 and '-,' in /home/oc-includes/osclass/core/Session.php on line 47

[Aficionado]

I see dev101 has opened this

https://github.com/osclass/Osclass/issues/1899

but no response at all.