Could not write to output file ‘Something.dll’ — ‘The directory name is invalid. ‘ – BizTalk Deployment

There is a simple solution for this.

This error might have occurred incase if you delete the temporary files from your PC.

Step1:
Just go to Run Command and Type %temp%

Step2:
It gives you an error saying that the directory is not found. Just go to that location and create that directory.

Now, try to redeploy the solution, the error goes away.

Some times you may need to give permission to that folder. Check the below link if you still have issues.

http://support.microsoft.com/default.aspx?scid=kb;en-us;825791

– Shiv