OpenX: M2M authentication error fix

We just received this error on our OpenX server after a version upgrade:
Dashboard Error: M2M authentication error – password invalid (code: 823). If this error repeats please describe your problem in detail and post it on the OpenX forum.

With the encouragement to post the error on the forum, naturally alot of people do. Actually, a quick search of the OpenX forums revealed that this question is posted on the OpenX forums almost once pr day, and people rarely get a response too. Why OpenX would not fix their product so that this error does not occur is beyond me, but the solution still was simple.

Read the solution