Error message when merging contacts

Question

Using Drupal 7.53 and civicrm 4.7.15.

Attempting to merge two contacts and get this message:

"Sorry but we are not able to provide this at the moment. Expected one RuleGroup but found 0" Return to home page.

Thanks.

Answer 1

This happened to us, and it turned out that we didn't have a "supervised" dedupe rule defined for individuals. You can have at most one "supervised" and one "unsupervised" dedupe rule. Our supervised rule had disappeared (though I haven't worked out how). I recreated it and the error disappeared. There's some relevant documentation here: https://docs.civicrm.org/user/en/latest/common-workflows/deduping-and-merging/#dedupe-rules