Some common HA log messages and their explanations are as follows:

Log: 

<Time> <LoadMasterHostname> ucarp[]: Bad digest -md2=[...] md=[...] - Check vhid, password and virtual IP address

Explanation

An interface used for HA checks is receiving a packet from a different interface/appliance.

How to solve

Check that the LoadMaster pair is using a unique HA-ID.

Check that an interface is not receiving packets from another interface. For example, eth0 is used for sending HA status but it is connected to the same switch as eth1. In this scenario, eth1 will see the packets and report this error message.

Log: 

<Time> <LoadMasterHostname> ucarp[]: [WARNING] HA Config file has changed - reloading

Explanation:

A user made changes to the HA parameters.

Log: 

<Time> <LoadMasterHostname> ucarp[]: [CRITICAL] Detected Active - Active re-arping

Explanation:

This message occurs when both LoadMasters become "Active". The LoadMaster that is set to "HA Mode First" (LM1) receives a CARP packet from "LM2". It detects another Active on the network, informs LM2 that the Active is up and healthy, and re-ARPs to update the routers/firewalls.

Log: 

<Time> LoadMasterHostname> ucarp []: [WARNING] Bad TTL

Explanation:

This means the machine sending the CARP message (this might not be a LoadMaster) is not on the same network. It is at least one hop away.

Log: 

<Time> <LoadMasterHostname> ucarp []: [WARNING] Switching to state: Active

Explanation:

The connection to the partner unit has been lost or the unit is not responding correctly to CARP messages.

How to solve:

Verify that the partner unit is up and running. Follow the tips in the General Troubleshooting Tips section and confirm all switch settings per the guidelines in the Confirm Settings section.