You noticed a couple of errors happening on a regular basis during the day related to:
MainController failure.
Object reference not set to an instance of an object.
[System.NullReferenceException @ Symantec.ActivityCenter.Api]
.....
HTTP [GET]: https://smp.example.com/altiris/activitycenter/api/trees/a57fb0e9-0676-4e00-929a-6bb37dc1f888/455ae0db-ec74-455b-b262-89421c96908d/591bfda4-ecf4-4d67-89a4-0f87fc2a67e5/keypath?search=Microsoft Silverlight - Uninstall2' &foldersOnly=false&includeHidden=false&includeRoot=false&includeGuidNodes=false
ip: [10.0.63.50]; languages: [en-US,en;q=0.9];
timings: [[R] 00:00:00.9021014(W: 00:00:00.0009962)];
response: [200 OK]; x-smp-nsversion: [8.5.5713.0];
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Date: 12/13/2021 2:48:20 PM, Tick Count: 1337403000 (15.11:30:03), Size: 7.11 KB
Process: w3wp (6876), Thread ID: 111, Module: Symantec.ActivityCenter.Api.dll
Priority: 1, Source: Symantec.ActivityCenter.Api.Controllers.ApiControllerExceptionHandlerAttribute.OnException
File: C:\ProgramData\Symantec\SMP\Logs\a.log
These errors happen after two client machines are trying to get their client policy but our process fails to generate the proper XML for multiple policies:
Unable to generate policy XML for item: 'Microsoft Silverlight - Uninstall2' (a8eb6c08-ed21-4931-bee9-72ccb12379d7), resource: 99e72466-2e3f-4c77-adc2-0a23ee41619e
At least about these two policies:
https://smp.example.com/altiris/activitycenter/api/trees/a57fb0e9-0676-4e00-929a-6bb37dc1f888/455ae0db-ec74-455b-b262-89421c96908d/591bfda4-ecf4-4d67-89a4-0f87fc2a67e5/keypath?search=Microsoft Silverlight - Uninstall2'&foldersOnly=false&includeHidden=false&includeRoot=false&includeGuidNodes=false
https://smp.example.com/altiris/activitycenter/api/trees/15ce669d-efdb-483b-9e2c-7e3aafc88093/77cd2974-8c40-4ae6-931e-fe60d87781a9/433329c8-f33d-4ed1-a9c0-82b4d66c2aa1/keypath?search='Symantec Endpoint Protection - NA x64 - 14.3.3384.100&foldersOnly=false&includeHidden=false&includeRoot=false&includeGuidNodes=false
We cleared/deleted both computer records from the SMP Console but that didn't help.
ITMS 8.x
The issue with the "MainController" errors seems to be related to possible corruption on those two client machines. Reinstalling the Symantec Management Agent resolved the issue: