In California, is a lease valid if not signed by all tenants? Thank you.

It is valid with regard to the tenants who have signed. They can be held responsible for the full amount of the rent.

Do you the civil code I can refer to? I read if all tenants do not sign it is not a binding lease.

I don't know of any civil codes that codify this. It is a general common law provision. Where did you read otherwise?

Are all the tenants named on the lease?

Most likely the lease will be deemed valid for the signators.

There is a total of two tenants and only one tenant signed the lease. Both incomes were also required to qualify because one income wasn't enough. I will look up the website as well.

https://www.askmehelpdesk.com/real-estate-law/valid-lease-if-not-signed-both-parties-named-lease-565422.html

The first answer says if not signed by both tenants listed on the lease then it is not binding. I also read it on another website and paste the link. I just want to be sure.

If you read further in that thread, the situation was different. I think there needs to be more info about the situation to determine the outcome.

Who wants to void the lease? How long have they lived there? Did the second tenant every move in? How is the lease worded as per tenants? What is the relationship of the two tenants?