CoreBOSBB

Sorry, I've written "I've seen that exist to errors." but is "I've seen that exist two errors." :-)

There are two errors. Your error when you try to show the value with the new relation with contact and the other is when you select the related module "Contacts" to show the contact list related whit a product.

I don't find field "vtiger_contactdetailsRelProducts812.firstname" in database.
Could you give me a little help to modify SQL request for this report please.

I had a look but it is not easy to solve. The code uses the relation between Products and Contacts that is on the "More Information" tab to dynamically generate part of the SQL while it sees your new relation field for the other part, that is where the conflict enters.
I dedicated some time but couldn't finish nor get back to it.
We will (sooner or later)

I just uploaded a fix that should make this report work correctly.
Please update your install, apply coreBOS changesets and let me know how it goes.

https://github.com/tsolucio/corebos/commit/3bbdae8cf6323dd55744288cf3103d4d6082ce37