The most common error experienced during the XI 2014 upgrade process is the following core config error:
CONFIG ERROR! Restart aborted. Check your Nagios configuration.
XI 2014 introduced some new mechanisms to guard against and remove the dreaded "ghost config" errors as well as some issues pertaining to escalations/dependencies. Due to these changes though, you may receive the above error during the upgrade, immediately after the installation of nagios core 4.
The most common resolution requires fixing the config errors in the CCM, writing and verifying the config, and then re-running the upgrade script. Enumerated steps are below:
Run ./upgrade until the error occurs. Do not roll back the VM or installation. XI will now be half-upgraded and the config errors will have to be resolved before the upgrade can continue.
In XI, browse to the CCM: Configure > Core Config Manager > Tools > Write Config Files.
Click "Write" and then "Verify". You should receive at least one error. The text of the error should be fairly descriptive concerning which object is having issues and what those issues potentially are. If you do not see any descriptive errors, you may have issues with escalations or service/host dependencies. You will most likely want to de-activate these definitions until the upgrade is complete.
Resolve the error in the Core Config Manager (CCM). An easy method is to de-activate the config item it is talking about as this will let you proceed past the problem and continue with the upgrade.
Once the detected errors are resolved, re-run the "Write" and "Verify" process from the "Write Config Files" tool. Resolve any further errors in the CCM, repeating the process above as many times as necessary until all config errors are resolved.
Only when the "Verify" process completes without and error should you proceed.
Click "Apply Configuration" - it should complete without error at this point.
Now, return to the shell and re-run ./upgrade. The upgrade process should continue past the core 4 upgrade and nagios process restart.
A more detailed explanation of the Write and Verify steps are outlined in this article:
Configuration Verification Failed
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