You might face the situation where the creation of an alternate key does not seem to do its job. It remains in the pending state:

When trying to reactive the key:

The system throws an exception saying “Reactive entity key is only supported for failed job”:

So, let’s take a look at the linked system job:

We have the very explanatory message saying “Exception: Event failed due to an exception”:

So we are only allowed to reactivate a key for a failed job, right? So a system job with an exception is not a failed job? Seems odd to me.

Let’s try to remove these “exception” system jobs:

Next, we are able to reactive the key(s) again:

Give it a few seconds, and your alternate key is Active:

Conclusion

When an entity key remains in the pending state, check the according system job and delete it if it has an exception. After deleting the system job you are able to reactive the entity key. Another mystery resolved!