Error Message :
This is just a short excerpt from the agent and PWP log file, please be aware that the following messages are just an example and may vary.
...

Agentlog:
U2000000 Started program UC4 Agent 'AGENT_NAME', version '10.0.8+build.498', changelist '7570585'.
U2000073 Connection to system 'AE_SERVER' via CP Server 'AE_SERVER#CP002' successfully established.
U2000098 Message from 'AE_SERVER#CP002' could not be decrypted (Ret='589824', minor='1002').
U2000143 General GSS error: 'Defective token, reason: 'Wrong parameter' (1002)'.
GSS state: 2
QOP : 3
TRACE: Invalid message recieved - 0x0085EF10, 00000264
00000000 30303030 30323634 5543343A 676C6F62 >00000264UC4:glob
< 00000010 616C3030 314E4154 20202020 20202020 >al001NAT
< 00000020 20202020 20202020 20202020 20202020 >
< 00000030 44303030 30323038 31302E35 382E3133 >D000020810.58.13
< 00000040 372E3738 3A353037 30333B31 302E3538 >7.78:50703;10.58
< 00000050 2E313337 2E37383A 35303530 343B3130 >.137.78:50504;10
< 00000060 2E35382E 3133372E 37383A35 30353032 >.58.137.78:50502
< 00000070 3B31302E 35382E31 33372E37 383A3530 >;10.58.137.78:50
< 00000080 3730343B 31302E35 382E3133 372E3738 >704;10.58.137.78
< 00000090 3A353035 30313B31 302E3538 2E313337 >:50501;10.58.137
< 000000A0 2E37383A 35303730 303B3130 2E35382E >.78:50700;10.58.
< 000000B0 3133372E 37383A35 30353033 3B31302E >137.78:50503;10.
< 000000C0 35382E31 33372E37 383A3530 3530303B >58.137.78:50500;
< 000000D0 31302E35 382E3133 372E3738 3A353037 >10.58.137.78:507
< 000000E0 30323B31 302E3538 2E313337 2E37383A >02;10.58.137.78:
< 000000F0 35303630 303B3130 2E35382E 3133372E >50600;10.58.137.
< 00000100 37383A35 30373031 >78:50701
U00011183 Client '1000', RunID '0085318525'. Message 'EXAKTJ' for Agent 'AGENT_NAME' was acknowledged with error code 63 (not connected). Job status will be changed to READY_FOR_RUN....

 The communication process (CP server) sends an unencrypted CP list message to the agent.
Afterwards the agent was not able to perform any action and was automatically disconnected from the system.  
  
Background information:
The communication process (CP server) sends an unencrypted CP list message to the agent. The Windows agent writes the error message:
U2000098 (message could not be decrypted) into the logfile, and terminates abnormally.
 

Cause type:
Defect
Root Cause: Bug, in the Automation Engine Server where the communication process (CP server) sends an unencrypted cp list message to the agent.

Release: AUTWAB99000-12.0-Automic Workload Automation-Base Edition
Component:

Update to a fix version listed below or a newer version if available.
 

Fix Status: Released

Fix Version(s):
Component(s): AE Server

Automation Engine 12.1.1 – Available

Workaround :
N/A