apmpacket service fails to start and apmpacketlog.txt shows "Warning: main: apmpacket is already running"

Products

• CA Application Performance Management Agent (APM / Wily / Introscope)
• INTROSCOPE

Issue/Introduction

On test environment an upgrade from TIM 10.2 to 10.5.2 was successfully tested and then rolled back by uninstall of 10.5.2. and install of 10.2.
However when trying to start the 10.2 apmpacket service it fails to stay up and apmpacketlog.txt file contains the following lines:

Tue Sep 4 17:09:26 2018 980 ***************************************************************************** 
Tue Sep 4 17:09:26 2018 980 CA Wily apmpacket starting 
Tue Sep 4 17:09:26 2018 980 Copyright (c) 2016 CA. All rights reserved. 
Tue Sep 4 17:09:26 2018 980 ***************************************************************************** 
Tue Sep 4 17:09:26 2018 980 ! Warning: main: apmpacket is already running, retrying 
Tue Sep 4 17:09:27 2018 980 ! Warning: main: apmpacket is already running, retrying 
Tue Sep 4 17:09:28 2018 980 ! Warning: main: apmpacket is already running, retrying 
Tue Sep 4 17:09:29 2018 980 ! Warning: main: apmpacket is already running, retrying 
Tue Sep 4 17:09:30 2018 980 ! Warning: main: apmpacket is already running, retrying 
Tue Sep 4 17:09:31 2018 980 ! Warning: main: apmpacket is already running, retrying 
Tue Sep 4 17:09:32 2018 980 ! Warning: main: apmpacket is already running, retrying 
Tue Sep 4 17:09:33 2018 980 ! Warning: main: apmpacket is already running, retrying 
Tue Sep 4 17:09:34 2018 980 ! Warning: main: apmpacket is already running, retrying 
Tue Sep 4 17:09:35 2018 980 ! Warning: main: apmpacket is already running, retrying 
Tue Sep 4 17:09:36 2018 980 ! Warning: main: apmpacket is already running, retrying 
Tue Sep 4 17:09:37 2018 980 ! Warning: main: apmpacket is already running, retrying 
Tue Sep 4 17:09:38 2018 980 ! Warning: main: apmpacket is already running, retrying 
Tue Sep 4 17:09:39 2018 980 ! Warning: main: apmpacket is already running, retrying 
Tue Sep 4 17:09:40 2018 980 ! Warning: main: apmpacket is already running, giving up 
Tue Sep 4 17:09:40 2018 980 main: apmpacket exiting with status 1 

Environment

CA APM TIM 10.x

Cause

Running command "ps -ef | grep apmpacket " confirms that no apmpacket process is already running.
Also these files created when an apmpacket is running do not exist:
/var/run/apmpacket.pid
/var/run/apmpacket/pid
/var/run/apmpacket/serversocket
It appears that the apmpacket process is checking something at startup and the result is indicating that something related to an existing apmpacket process still exists. It maybe something left over from the 10.5.2 uninstall and reinstall of 10.2.

Resolution

Restarting the Linux server cleared the problem.