To be able to use Free Text field 1 in Basecone, this following two settings needs to be enabled first in both Basecone and in Twinfield.
If you are getting the error above, follow the instructions in step 2.
Step 1: Settings in Basecone
Go to the followings settings in Basecone:
Settings > Company > Action  > Settings (tab)
Enable the setting for free text field available to Yes.
Step 2: Settings in Twinfield
Go to the following settings in Twinfield:
Settings > Company settings > Transaction types > Purchase invoice.
Change the following settings in the column for Free Text field 1:
Usage --> Allowed
Location --> Total and detail line