ERROR:unable to attach to application INFOPATH.exe

Yesterday I started digging in one of my company's projects. It's some kind of messy request acceptance system that is coded in c# on top of InfoPath using a SharePoint server. Although the project is small, we had some hard time configuring it to run on my machine. Finally after spending couple of hours adding a bunch of mysterious files and registry settings it started. So far so good. Now I tried to run the project in Debug, but the IDE complained with the following error, although the project itself was running "properly".

What provoked me to write this entry is not the error, but the fact that this should be the rarest error ever. Why do I think so? Because doing a Google search on the error itself, which usually returns thousands of results, gave me just four pages. Luckily, the solution was on one of them. I hope, after some time, this page will become the fifth one listed in the results :)

Here is the solution itself, it is stolen from Alain Vézina's blog Lanwalker - Brain Dump.

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Create a file named infopath.exe.config in the folder where InfoPath.exe is located (typically, C:\Program Files\Microsoft Office\OFFICE11), with the contents:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<startup>
<requiredRuntime imageVersion="v1.1.4322" version="v1.1.4322" />
<supportedRuntime version="v1.1.4322" />
</startup>
</configuration>

This will force InfoPath.exe to use .Net 1.1