This error is returned by Facebook API, as the number of checked items and frequency of checks is causing too many API calls. Basically, if you have too many items checked or multiple rules checking at the same time, this might cause Facebook API to return such error.

In order to resolve this, please follow the instructions below:

1) Please narrow down the rule scope to decrease the number of checked items by applying various filters (”Name contains”, “Hours since creation", “Status is”

Besides, you can use Campaign/ Ad set/ Ad metrics to exclude items that have not been active/spending recently:

For example, the rule below will check only those campaigns that had any spend within last 14 days. You can build similar filters using Impressions, CPM, Frequency, Reach:

2) Change the rule schedule to decrease the frequency of rule checks

You can either choose a less frequent option, e.g. "Every hour" or set a custom schedule with at least 1-2 hours breaks.