Error while Creating WebService Or Automation Service after upgrade

Error while Creating WebService Or Automation Service after upgrade

Below error received while starting a new Web Player service or Automation service
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Unhandled Exception: System.IO.FileLoadException: Could not load file or assembly 'log4net, Version=2.0.8.0, Culture=neutral, PublicKeyToken=669e0ddf0bb1aa2a' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)
: 45a7359b-eb9e-4c32-afa2-3f12f2d73dd0 [AUTOMATION_SERVICES] process state switched to failure with exit value -532462766
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Cause:
You may have a custom built component/extension deployed to the Deployment Area which may not be compatiable with the upgraded version

Rebuild the package and deploy the extension
or
Remove the Custom package/extension and you should be able to start the service