Lock a field after saving a record in Dynamics 365 with Business Rule

I will show you how to lock a field after saving a record in Dynamics 365 with Business Rule and without Javascript.

Guys, I finally found an answer for this. For Business rules conditions to work, "THE FORM MUST HAVE THE FIELD ON IT".

I wasted so much time before finding this hidden fact!. Business rules are the best option to do this.

I had the exact same challenge: I need to lock a set of fields only after the initial record has been saved.

Innocently I went about with a business rule that if "Created On" Contains data... I went ahead and lock the fields.

Well, this would not work for the longest time and I could not figure it out until I tested the condition against a different field that was in the form. And then it worked. WoW! I added the 'Created On' field on the footer of the form, and from that point on, all worked as expected.

MS: Wouldn't be nice to validate the rule and warn the user about a field referenced that is NOT in the form? that way the validation function will do something useful for once.