Process Builder and the subtlety of the “execute actions only when” option

Question

This one eluded me for several years. I have always been intrigued by the Process Builder option “Do you want to execute the actions only when specified changes are made to the record”. It’s pop-up help and its complete help page never enlightened me much. But today I really had to understand this concept, because I had a problem that was directly related to it.

The process on which I am working has several conditions (with actions of course) and the actions and conditions are dependent on each other. So the order of the conditions in the process is important, but I had figured that one out. The first condition checks whether some boolean is true, with the option “Do you want to execute the actions only when specified changes are made to the record” set. When I test this, it looks like only this first condition is taken into account. And its actions are executed only once, and never after that first time.

Answer 1

The phrasing of the option “Do you want to execute the actions only when specified changes are made to the record” turns out to be very subtle. I had always interpreted this as “If the boolean changes to true, execute the actions, otherwise go to the next condition”. But this is not how it works. When the condition is evaluated, the option is not taken into account. That is, the condition evaluates to true or false and depending on that, you go either to the actions or to the next condition. Only when you go to the actions, does the option come into play. If the boolean had changed so that the condition is now true, but wasn’t before, then the actions are executed. Else not.

So if my boolean is always true, the process will never get past the first condition. The first time it will execute actions, all other times it will not do anything at all.

To make a condition + actions work when values change, you must use a formula that uses PRIORVALUE.