I\'m having an odd issue with Expression Blend 4. I\'ve been using Blend 4 in conjunction with Visual Studio 2010 for quite a while without incident (beyond the ultra-frequ
You can also quickly solve this issue by adding a Debug config back into your solution:
Create another Configuration called 'Debug' placed first in the list of configurations.

You can do this in two ways:
1) Rename an already present configuration to 'Debug'
- Open the Configuration manager
- Expand the 'Active solution configeration' dropdown
- select and you can edit or delete any of the configurations present.
2) Add a new configuration.
- Follow instructions above, and then
- You will need to reorder the configurations in your solution file manually.
Hope this helps...