Eviction included roommate that had moved out (US-CA)

Location: California
A relative of mine is having a problem. He was initially on a rental lease as a roommate, but moved out after 2 years. The leasing office staff were notified of this on multiple occasions, but never updated the lease to reflect the change. On all subsequent lease agreements, he was named as a resident and the lease was signed without his signature on it for 7 years.

Recently, the residents at that apartment were evicted, and since my relative was on the lease still he was named on the eviction. He was planning on moving but that will be much more difficult with an eviction on his record. What legal recourse would he have to get this cleared up with the court and credit bureaus? He never signed the lease himself and was never given a chance to defend himself in court.