Solution Ideas:
There must be a copy in a folder, and the results are predictable.
The current date is March 10, 2016, but
C:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP. files\root\fd1302ff\6f7481f8\ assembly\dl3\831cbe7c\a10a72a2_8c7ad101\xxxx. DLL March 4, 2016
C:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP. files\root\fd1302ff\6f7481f8\ assembly\dl3\831cbe7c\a10a72a2_8c7ad101\xxxx. DLL March 9, 2016
C:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP. files\root\fd1302ff\6f7481f8\ assembly\dl3\831cbe7c\a10a72a2_8c7ad101\xxxx. DLL March 10, 2016
Understand here, is Microsoft's framework generated cache files caused, deleted March 4 and March 9, run up, you can debug breakpoints.
Note: The red is the system randomly generated folders, files to be global search to be done.
This problem is caused by:
The source code of the site once debugging, and replaced the other directory, the results of debugging will appear this problem. To put it bluntly, every debug will be thrown into the cache.
Resolve an issue that cannot be debugged in VS2013 Debug asp: The breakpoint is not currently hit. A copy of XXX.cs was found in XXXX.dll, but the current source code differs from the built-in version in XXXX.dll.