My application server logs reported the following error when the Introscope agent was used:
The Enterprise Manager in this case was version 10.1, the monitored application was running in Weblogic and a 9.1.7 agent was used.
In this case, a 10.1 agent had been installed at the same location previously. There is a new automatic entry point detection feature in APM 10 agents which creates a pbd called AutoPersist.pbd that is placed in the hotdeploy folder. When using the 9.1.7 agent in the same folder hierarchy as the 10.1 agent, the AutoPersist.pbd was still present in the hotdeploy folder but any agent before APM 10 does not have the code available (EntryPointTracer) to be able to use the feature, hence the error message. If you read the pbd, you will see the classes and methods that we had detected, in this case relating to Weblogic.
For the particular case here, the AutoPersist.pbd should be removed from the hotdeploy folder, for this the application would need to be stopped.
The code required is in the core Agent.jar file from APM 10 so if you see this error with APM 10 agent, there would be a different cause which would need further investigation with the Support team.
It is possible to have multiple versions of the agent on the same machine running concurrently.
It is also possible to have an absolute path for hotdeploy folders, such that the hotdeploy folder could be shared by different agents.
As a best practice therefore, please make sure you do not share hotdeploy folders between pre-APM 10 and 10.x and higher agents to avoid this problem.
For more information about the automatic entry point detection feature feature, you can review the documentation for APM 10.1 at this location: