InfoPath does not support customizing the form used for this list.

Is it possible to customize document library forms using InfoPath?

Tricky question right? If you face this error message then several questions will be raised as:

InfoPath does not support customizing the form used for this list.

Is this restricted to this document library only?

Is this a default behavior?

Is it applicable to forms library only? And so on….

But let me tell you-this is a by design and error message won’t be there in the next version. Here is the detail on that:

Refer this link: http://blogs.msdn.com/b/infopath/archive/2009/12/17/customize-a-sharepoint-list-form-using-infopath-2010.aspx?PageIndex=1#comments

You need to look for the command for the detail explanation:

We don't support customizing document library forms in InfoPath. This error should not appear in the final released product.

Laura Harrington (InfoPath Team)

This is restricted to document libraries only and works fine with the SharePoint Lists/custom lists.

If you open any list and refer the same settings then you will get the option to make it enable or not by selecting Yes/No option.

If you have any queries/questions regarding the mentioned information then please let me know, Thank you.