asp.net mvc 4 - How to permanently teach Visual Studio to detect my debugging information? -

using visual studio 2012, maybe you've seen message, too:

it says:

the following module built either optimizations enabled or without debug information:

c:\windows\microsoft.net\framework\v4.0.30319\temporary asp.net files\root\6dce49fa\6c454827\assembly\dl3\95d61873\9871ffdd_4288ce01\noedownloadbereichweb.dll

to debug module, change project build configuration debug mode. suppress message, disable 'warn if no user code on launch' debugger option.

in past got maybe once week when starting debug asp.net application , resolved recompiling solution.

recently switched iis express happens every second/third time want debug code after did changes.

i resolve 1 or of following steps:

• rebuild application (helps of time)
• close iis express , rebuild application
• reboot windows 8 , rebuild application

i've found similar questions here , on google , still not able permanently resolve this.

my question:

can imagine causes behaviour every , then?

update 1

the error seems related with/followed asp.net error messages (german):

das erstellen von "system.net.http.extensions" oder das erstellen einer schattenkopie ist nicht möglich, wenn diese datei bereits vorhanden ist.

which rougly translates english:

cannot create/shadow copy "system.net.http.extensions" when file exists.

(the refered file name "system.net.http.extensions" randomly changed asp.net)

update 2

i've switch visual studio development server , got rid of errors described above:

don't know whether on system, or what's reason it.

go tools > options > debugging > general > enable code > warn if no user code on launch