mount error(126): **Required key not available**
Refer to the mount.cifs(8) manual page (e.g. man mount.cifs)

May 16 17:49:02 computer1234 cifs.upcall: get_cachename_from_process_env: pathname=/proc/1234/environ
May 16 17:49:02 computer1234 cifs.upcall: get_existing_cc: default ccache is FILE:/tmp/krb5cc_12345678
May 16 17:49:02 computer1234 cifs.upcall: get_tgt_time: unable to get principal
May 16 17:49:02 computer1234 cifs.upcall: krb5_get_init_creds_keytab: -1765328174
May 16 17:49:02 computer1234 cifs.upcall: Exit status 1