Error "There is no source code available for the current location."

I added the AjaxControlToolKit's sample DLL file as a reference to my web application. I used Mask text boxes on my pages.

While debugging the application, it first asked me to open MaskedEditExtender.cs file. So I just search it from my physical location and copied it in the Bin folder of the solution. Well ... now it is not asking for opening that file. But while debugging, after the content page, it debugs the master page as expected, but after just finishing debug of the master page, the debugger traverses to the MaskedEdit开发者_如何转开发Extender.cs file...

That is not much of an issue. That's fine (I am curious why this happening), but while debugging the MaskedEditExtender.cs file, it pop ups the message

There is no source code available for the current location."

with two buttons, "OK" and "Disassembly". What is this error? Why is it arriving? How do I avoid it?

---

You're missing the PDB file (program debug database) of the assembly where the exception occurs.

---

Open the Breakpoints window, locate the breakpoint, and delete it. This helped me...

---

You have arrive at a section of your program for which the debugger cannot associate a source code file. Either this is some third-party software for which you do not have the source code.

Or you have the source, but the debugger cannot associate the debugged code to that source file, since you are missing the debug symbols file (the PDB file). This file contains the mapping between the lines in the text source files and the memory address assigned by the compiler to your methods and members.

It could help if you would specify what method you are trying to drill down into when you get this message.