I have just installed APM connector V 3.6.5.
APM connector not coming online with this error in the APM_Connector.log
APM Connector Initialize failed: (401) Unauthorized
Release : 4.2
Component : Catalyst Connector for APM
Here's the steps to fix the problem. The encrypted value for the EMConnectionPassword field seem too long, not sure if it's correct.
Edit \soi\resources\Configurations\APM_<IP or Hostname>.xml
Copy the EMConnectionPassword value from a backup copy or re-encrypt the EMConnectionUser's password and paste it in the xml file.