InfoPath won't let me customize forms for list

Question

When i try to create a custom InfoPath form on my Orders List I get the following error:

The SharePoint list form can't be customized with InfoPath because fields of an unsupported data type are marked as required, or because fields are corrupted. In SharePoint, try deleting the columns or editing the column properties to remove the required attribute. - Product (Lookup)

Additional information:

The Site contains;

• Two Site Content types Product and Order. Order does have a lookup field to product, it is a optional field so NOT required.

• Two Lists. A Products list with Product as Content Type and an Orders list with Order as Content type.

The Site Collection has the SharePoint Server Enterprise Site Collection features activated. Creating custom InfoPath forms for the Products lists works without any problem.

I tried to delete my List and recreate it but it i still get the same error. Hope someone can help me with this issue.

Thanks

Answer 1

Apperantly this was due to to the Title field in the Content Type being a required value. Changing the lookup to the items ID solved it.

This worked for me. But if you don't want to use the ID field in your views or on the form, here are a couple tips to replace it with the Title (or other column) in your lookup field...

Replacing the IDs in the form: In InfoPath, create a new data source for the lookup field. Follow through the prompts to find the list to lookup. Once it's added, change the Value to ID. This will now set the dropdown list in the form to display the Title values as well as properly link the IDs in the list.

Use Title (linked to item) in your list view without instead of the ID: Create a new index in the list you're looking up for the field you want to be linked. Then go back to the main list and change the lookup back to Title (linked to item). Note that this will again break the ability to edit the form in InfoPath. Changing it back to ID will allow InfoPath editing again. Then just change it to Title (linked to item) again when done. There's probably a "right" way to do this but it works for me.