I built solution, created application in IIS and mapped it to the application folder. It works fine. Then I go to “Attach to Process”, there are two w3wp.exe processes in list, but for one of them I get error “Unable to attach the process. A debugger is already attach.” I’ve googled it but I can’t find solution for my problem.
Answers:
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Method 1
I have installed Debug Diagnostic Tool v2.0 and as a result I have Debug Diagnostic Service which is started automatically and attached to one of w3wp processes. After turning off and disabling this service all works fine.
So the general rule: if you get such error check processes in task manager which can capture your w3wp process.
Method 2
You have 2 instance of VS and two entries in IIS running on the same application pool, for instance Both Server and Intranet are running on the same application pool.
=> Solution open IIS :
° Select the site and click ‘Basic Settings’ : Here you can check/select
the application pool used.
° Click on the “Application Pools” node (right under your computer name)
=> You get a list of defined application pools.
° Right click under the last one defined to open the context menu and
select ‘Add Application Pool…’
Create a new name and give it the same parameters that the one that was used
by your site.
° Select the ‘Basic Settings’ of one of your sites and change its application
pool to the new one just created.
=> Now Server and intranet have different application pools and your can
debug the both at the same time.
Hope this helps.
Method 3
For me, even after disabling the Debug Diagnostic Tool v2.0 this issue didn’t fix. So, I rebuild my webservice, pushed the DLLs on the IIS and restarted the it, which fixed the issue for me.
This issue may occur when you make changes in the your web service which is hosted on your local IIS and those changes are not pushed.
Method 4
Debug Diagnostic Tool v2 Update 2
https://www.microsoft.com/en-us/download/details.aspx?id=49924
Can use this link if the link provided by @mtkachenko above doesn’t work
Method 5
Have this in Visual Studio 2019 but after the debugger crashes on occasion. Without restarting the PC, which can be a slow affair, create a temporary second application pool and switching the site over to the new app pool in IIS also works.
Method 6
Really odd – but this simple thing works for me:
- Go to some file in your main project.
- Go to Project menu and choose Set as start-up project.
This might seem redundant if you’ve already chosen that project as the start-up project before, but it seems to work.
All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0