PAM Authentication Deadlock & Worker Thread Freeze

MaxScale instance (Version: 25.01.3) crashed and performed an automatic restart at 02:44:26

At 02:24:40 timeout (SIGTERM) was issued for /usr/bin/maxscale_pam_auth_tool during user authentication

From 02:24:41 to 02:26:00 : MaxScale flooded the log with continuous  timeout (SIGKILL) errors trying to terminate it.

02:25:30 & 02:26:00  The deadlock caused Worker-02 to freeze and stop reporting back.

02:26:01 : The watchdog was triggered. GDB failed to generate an external output, an internal stacktrace was not dumped, and the process restarted.

2026-07-15 02:24:40   warning: (2815) Soft timeout for command '/usr/bin/maxscale_pam_auth_tool', sending SIGTERM

2026-07-15 02:24:41   error  : (2815) Hard timeout for command '/usr/bin/maxscale_pam_auth_tool', sending SIGKILL

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2026-07-15 02:25:30   warning: Thread 'Worker-02' has not reported back in 30 seconds.

2026-07-15 02:26:01   notice : GDB failed to produce output, generating stacktrace in MaxScale.

2026-07-15 02:44:26   notice : MariaDB MaxScale 25.01.3 started

The backend database XXX_XX-XX continuously requests the dialog plugin for the user YYYYY, but MaxScale logs that only mysql_native_password is supported.

2026-07-15 02:51:21   error  : (52) [MariaDBAuth] 'XXX_XX-XX' asked for authentication plugin 'dialog' when authenticating 'YYYYYY'@'ZZ.ZZZ.ZZ.ZZZ'. Only 'mysql_native_password' is supported.