InfoPath forms have a default control for attaching/uploading files, called File Attachment. You can find it on the Design Tasks pane (View –> Design Tasks), under Controls within the File and Picture section. You can easily drag and drop the control unto your form in design mode.
InfoPath team blog has a post on this, which also explains the blocked file types (such as exe and bat).
aspnetForm.encoding = "multipart/form-data";
Kept getting this error last week after an InfoPath form had been updated. This happened every time I tried to open up (create) the published form from the form library. In Design mode I looked through all the fields and controls again, assuming I’ve made a mistake, but no mistakes were made.
There was however, something that was staring me in the face, which I hadn’t realised. I had actually changed a “Pull-Down Menu” control to a “Free-Text Box” control within the form. Initially, the pull-down menu control was set to use lookup values that were stored on a SharePoint list, and a data connection was configured for this.
Now that the control is free-text, there was no reason for the lookup values to be reference in the form. I removed the particular data connection, and republished the form, needles to say no more annoying Form Processing errors. Lesson learnt? Always check for stray connections, controls, reference etc etc…
It’s quite easy setting up a column within an InfoPath repeating table to auto-number. Please see the list of steps to get this done listed below:
1) Double-click the intended column to get into it’s properties.
2) On the Data tab, under Default Value click on the fx (formula) button.
3) Within the Insert Formula box type this in Count(../preceding-sibling::*) + 1
4) Click OK twice, and you’re done.
5) The above formula starts with 1. If for example 10 is used, then the numbering starts from 10.
Hope this helps.