BigIP LTM Pool Monitors Stuck on "Checking"

This morning a similar issue was discussed with a customer (running v11.4.1).

Monitors on one machine (in a sync-failover device-group) remained in "checking" (blue) state after power-on.

(Unfortunately no qkview was pulled before he tried to fix the problem.)

In /var/log/ltm.1.gz I noticed multiple log entries as follows:

err mcpd[7267]: 01070712:3: Caught configuration exception (0), Can't find monitor rule: 3065 - ltm/validation/MonitorRule.cpp, line 992

I guess there was an inconsistency with the binary configuration file (typical symptoms as config sync failure, archive save failure did not apply).

He fixed the situation by changing the pool configurations (similar approach as described in the initial post) which probably forced mcpd to save the config to the binary configuration file.

(Please note, that after a boot the configuration will be loaded from binary configuration files by default.)

Ideally one would open a support case before trying to workaround.

If there is no time to get it handled by support, I would try to stop mcpd, delete the binary configuration files, start mcpd and load the configuration from the text configuration files.

Happy new year to everyone monitoring this thread! 🙂