Many researchr operations suddenly fail because of the new validation policy, even though the field that triggers the validation error has not been changed.

I suspect that these fields have null values, which are now forbidden (apparently).

Submitted by Eelco Visser on 17 March 2011 at 20:34

At least for these simple value types the problem can be fixed with an update of the database

 update _Publication set _conferenceYear = '' where _conferenceYear is NULL;

null value is allowed (unless a validation rule explicitly prevents it), null dereference is not allowed

see https://yellowgrass.org/issue/WebDSL/351