Diagnosis:

If you are receiving one of the following errors, you can check the certificates by:

1. Navigating to <InstallDir>:\Program Files (x86)\Flexera Software\FlexNet Manager Platform\DotNet\bin on the  Batch Server 

 2. For the FlxCore.dll, FlxCore64.dll, FlxLicensingClient.dll and FlxClientCommon.dll, check the digital signature by:

2.a Right click the file(s)
2.b Properties 
2.c Digital Signatures
2.d Select the Certificate
2.e Details
2.f View Certificat 
2.g Certification Path
2.h Check the Certificate status box states "This Certificate is OK"
2.i Repeat from step 2.f for each certificate in the Certificate Path

3. For the FlxCore.dll, FlxCore64.dll, FlxLicensingClient.dll and FlxClientCommon.dll, you will also want to check the validity of each file by: 

3.a Downloading Microsoft SignTool from https://learn.microsoft.com/en-us/windows/win32/seccrypto/signtool
3.b Opening an administrator command prompt
3.c Changing directory to where signtool .exe is stored usually <Install Dir>:\Program Files (x86)\Windows Kits\10\bin\XX.XX.XX\x64
3.d Run signtool verify /pa "<FILE DIRECTORY HERE>"
3.e Check if the command prompt output is "Successfully Verified"

4. If your web server is separate from your batch server, the FlxCore.dll, FlxCore64.dll, FlxLicensingClient.dll and FlxClientCommon.dll should also be checked on the web sever using the same process as above. 

Solution: