Error 'Thread was being aborted.'

I got this error today for my app,

Server Error in '/asknlearn' Application.

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Thread was being aborted.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.Threading.ThreadAbortException: Thread was being aborted.

Source Error: 

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace: 

[ThreadAbortException: Thread was being aborted.] System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +486 System.Web.ApplicationStepManager.ResumeSteps(Exception error) +501 System.Web.HttpApplication.System.Web.IHttpAsyncHandler.BeginProcessRequest(HttpContext context, AsyncCallback cb, Object extraData) +123 System.Web.HttpRuntime.ProcessRequestInternal(HttpWorkerRequest wr) +379

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Version Information: Microsoft .NET Framework Version:2.0.50727.3615; ASP.NET Version:2.0.50727.3618

i had no idea, on how to solve it, tried everything, end up, cause of problem was there was a 'stray' file in the app_code folder (sync.ftl) that was created when developer sync there folder, and that file is accidentially added to app_code, apprantly app_code runs everything incl stray file and hence the error, delete the stray file, and problem is solved.