Take a very long path, under the 248/260 character threshold (construct your own file path for this to test), map to workspace where the local folder root path exceeds the length of the Project Path and thus puts the full path over 260 characters, ambiguous exception is thrown.

TECoreException: TF400898: An Internal Error Occurred

No explanation is provided to the source of the error or the offending line.
Trimming the overall path (eg: shorter job name) to <260 chars will result in successful 'get'.

Folder Path:
$/path/to/sampleApplication/branchname
Workspace root:
/build/workspace/TFSTest/TestLongJobName_Reaching_Almost_64_Characters

{{Checking if there exists a mapping for /build/workspace/TFSTest/TestLongJobName_Reaching_Almost_64_Characters...no.
Creating workspace 'Hudson-Test_LongPath_Reaching_Almost_64_Characters-jobnode1' owned by 'builder1'...
Mapping '$/path/to/sampleApplication/branchname' to local folder '/build/workspace/TFSTest/TestLongJobName_Reaching_Almost_64_Characters' in workspace 'Hudson-Test_LongPath_Reaching_Almost_64_Characters-jobnode001'...
Created workspace 'Hudson-Test_LongPath_Reaching_Almost_64_Characters-jobnode001'.
Getting version 'C189000' to '/build/workspace/TFSTest/TestLongJobName_Reaching_Almost_64_Characters'...
FATAL: hudson.remoting.ProxyException: java.lang.RuntimeException: com.microsoft.tfs.core.exceptions.TECoreException: TF400898: An Internal Error Occurred. Activity Id: 05d4637f-e7f2-4002-8b6c-3b195308a5d6.
hudson.remoting.ProxyException: com.microsoft.tfs.core.ws.runtime.exceptions.SOAPFault: TF400898: An Internal Error Occurred. Activity Id: 05d4637f-e7f2-4002-8b6c-3b195308a5d6.
at com.microsoft.tfs.core.ws.runtime.client.SOAP12Service.examineResponseDOMForFault(SOAP12Service.java:117)
at com.microsoft.tfs.core.ws.runtime.client.SOAPService.examineBodyForFault(SOAPService.java:987)
at com.microsoft.tfs.core.ws.runtime.client.SOAPService.executeSOAPRequestInternal(SOAPService.java:665)
at com.microsoft.tfs.core.ws.runtime.client.SOAPService.executeSOAPRequest(SOAPService.java:444)
at ms.tfs.versioncontrol.clientservices._03._Repository5Soap12Service.updateLocalVersion(_Repository5Soap12Service.java:1170)
at com.microsoft.tfs.core.clients.versioncontrol.internal.WebServiceLayer.updateLocalVersion(WebServiceLayer.java:3067)
Caused: hudson.remoting.ProxyException: com.microsoft.tfs.core.exceptions.TECoreException: TF400898: An Internal Error Occurred. Activity Id: 05d4637f-e7f2-4002-8b6c-3b195308a5d6.
at com.microsoft.tfs.core.exceptions.mappers.TECoreExceptionMapper.map(TECoreExceptionMapper.java:92)
at com.microsoft.tfs.core.exceptions.mappers.VersionControlExceptionMapper.map(VersionControlExceptionMapper.java:43)
at com.microsoft.tfs.core.clients.versioncontrol.internal.WebServiceLayer.updateLocalVersion(WebServiceLayer.java:3081)
at com.microsoft.tfs.core.clients.versioncontrol.internal.WebServiceLayer.updateLocalVersion(WebServiceLayer.java:3114)
at com.microsoft.tfs.core.clients.versioncontrol.UpdateLocalVersionQueue.sendToServer(UpdateLocalVersionQueue.java:769)
at com.microsoft.tfs.core.clients.versioncontrol.UpdateLocalVersionQueue.flush(UpdateLocalVersionQueue.java:461)
at com.microsoft.tfs.core.clients.versioncontrol.UpdateLocalVersionQueue.close(UpdateLocalVersionQueue.java:409)
at com.microsoft.tfs.core.clients.versioncontrol.engines.internal.GetEngine.processOperations(GetEngine.java:1054)
at com.microsoft.tfs.core.clients.versioncontrol.engines.internal.GetEngine.processGetOperations(GetEngine.java:808)
at com.microsoft.tfs.core.clients.versioncontrol.soapextensions.Workspace.get(Workspace.java:2459)
at com.microsoft.tfs.core.clients.versioncontrol.soapextensions.Workspace.get(Workspace.java:2341)
at com.microsoft.tfs.core.clients.versioncontrol.soapextensions.Workspace.get(Workspace.java:2331)
at com.microsoft.tfs.core.clients.versioncontrol.soapextensions.Workspace.get(Workspace.java:2308)
at hudson.plugins.tfs.commands.GetFilesToWorkFolderCommand.call(GetFilesToWorkFolderCommand.java:72)
at hudson.plugins.tfs.commands.GetFilesToWorkFolderCommand.call(GetFilesToWorkFolderCommand.java:18)
at hudson.remoting.UserRequest.perform(UserRequest.java:208)
at hudson.remoting.UserRequest.perform(UserRequest.java:54)
at hudson.remoting.Request$2.run(Request.java:360)
at hudson.remoting.InterceptingExecutorService$1.call(InterceptingExecutorService.java:68)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Caused: hudson.remoting.ProxyException: java.lang.RuntimeException: com.microsoft.tfs.core.exceptions.TECoreException: TF400898: An Internal Error Occurred. Activity Id: 05d4637f-e7f2-4002-8b6c-3b195308a5d6.
at com.microsoft.tfs.core.clients.versioncontrol.soapextensions.Workspace.get(Workspace.java:2470)
at com.microsoft.tfs.core.clients.versioncontrol.soapextensions.Workspace.get(Workspace.java:2341)
at com.microsoft.tfs.core.clients.versioncontrol.soapextensions.Workspace.get(Workspace.java:2331)
at com.microsoft.tfs.core.clients.versioncontrol.soapextensions.Workspace.get(Workspace.java:2308)
at hudson.plugins.tfs.commands.GetFilesToWorkFolderCommand.call(GetFilesToWorkFolderCommand.java:72)
at hudson.plugins.tfs.commands.GetFilesToWorkFolderCommand.call(GetFilesToWorkFolderCommand.java:18)
at hudson.remoting.UserRequest.perform(UserRequest.java:208)
at hudson.remoting.UserRequest.perform(UserRequest.java:54)
at hudson.remoting.Request$2.run(Request.java:360)
at hudson.remoting.InterceptingExecutorService$1.call(InterceptingExecutorService.java:68)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
at ......remote call to jobnode001(Native Method)
at hudson.remoting.Channel.attachCallSiteStackTrace(Channel.java:1654)
at hudson.remoting.UserResponse.retrieve(UserRequest.java:311)
at hudson.remoting.Channel.call(Channel.java:905)
at hudson.plugins.tfs.model.Server.execute(Server.java:233)
Caused: java.lang.RuntimeException
at hudson.plugins.tfs.model.Server.execute(Server.java:237)
at hudson.plugins.tfs.model.Project.getFiles(Project.java:264)
at hudson.plugins.tfs.actions.CheckoutAction.checkout(CheckoutAction.java:63)
at hudson.plugins.tfs.TeamFoundationServerScm.checkout(TeamFoundationServerScm.java:352)
at hudson.scm.SCM.checkout(SCM.java:495)
at hudson.model.AbstractProject.checkout(AbstractProject.java:1212)
at hudson.model.AbstractBuild$AbstractBuildExecution.defaultCheckout(AbstractBuild.java:566)
at jenkins.scm.SCMCheckoutStrategy.checkout(SCMCheckoutStrategy.java:86)
at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:491)
at hudson.model.Run.execute(Run.java:1737)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:43)
at hudson.model.ResourceController.execute(ResourceController.java:97)
at hudson.model.Executor.run(Executor.java:421)

}}