Galera error about TLS certificate with spaces in CN is vague

A space in a hostname is illegal but those can still appear in TLS certificates as the CN value. The error message for this case is extremely vague and gives no indication that the root cause of the failing SST is the TLS certificate. For a Galera layman like myself, Bad remote auth string sounds like wsrep_sst_auth being the problem which was not the case.

Sep 01 21:06:15 vm1-galera-000 mariadbd[80670]: 2026-09-01 21:06:15 2 [Warning] WSREP: Illegal character in variable: 32 ( ).

Sep 01 21:06:15 vm1-galera-000 mariadbd[80670]: 2026-09-01 21:06:15 2 [ERROR] WSREP: Bad remote auth string. SST canceled.