When trying to upgrade a LC7 process in Workbench, which is working fine under the LC7 compatibility layer you may receive an internal error in the upgrade report, with the following exception in the detail dialog:
at com.adobe.lcide.upgrade.lc8.dom.impl.ProcessRepositoryImpl.copyOutRoutes(Unknown Source)
at com.adobe.lcide.upgrade.lc8.dom.impl.ProcessRepositoryImpl.copyRouteInformationToBranch(Unknown Source)
at com.adobe.lcide.upgrade.lc8.dom.impl.ProcessRepositoryImpl.processBranch(Unknown Source)
at com.adobe.lcide.upgrade.lc8.dom.impl.ProcessRepositoryImpl.orchestrateProcess(Unknown Source)
at com.adobe.lcide.upgrade.lc8.app.UpgradeEngine.performUpgrade(Unknown Source)
at com.adobe.lcide.upgrade.lc8.pres.wizard.page.UpgradePageModel$UpgradeJob.run(Unknown Source)
This will be related to a particular QPAC in the process which does not have the correct mapping file for the Upgrade Process Tool. The report will show you on which QPAC the exception occurred, or you can remove each QPAC from the process one after the other, and re-test to isolate the problem QPAC.
Once you know what QPAC causes the issue, you should ensure you have the current upgrade mapping file for that QPAC loaded in Workbench. If the QPAC is from another vendor, then contact that vendor for the latest mapping file, and load it into Workbench under Preferences -> Upgrade Process Tool.