Object reference not set to an instance of an object error while calling an Action in Dynamics 365

Recently in one of our JavaScripts which was calling an action (with a plugin registered to it) was giving us the below error.

We had a plugin registered on the call of that action, which in turn was calling an external service.

We figured out the probable cause of this error (related to certificates) and updated the plugin code accordingly on the server.

Unfortunately, this didn’t fix the issue for us, we also tried different possible solutions but to no avail.

As a last resort, we thought of giving this a try – deactivate and activate the Action, and to our surprise that did the trick.

Our thought is maybe Action was somehow still referring to the old plugin code, and the step of deactivating/activating the Action kind of cleared the cache or something, making action to refer to the latest plugin code deployed.

Hope it helps..