I am getting something similar. After installing S-Server 7.4.0 and then 7.4.1 (r28740), my SBC claims an upgrade waiting, but will not upgrade. The upgrade downloads, starts to verify, then I get this message:  "Upgrade failed. There was a problem upgrading this remote. Please try again, or contact support."
 
I am using a Duet with Windows XP and wireless networking. Fortunately, the Duet continues to work otherwise.

(In reply to comment #1)
I forgot to note that I repeatedly have tried turning off and rebooting the SBC, at first with the power button, then by removing the battery, but that it hasn't helped.

Mike: the error you are describing is bug 8414.  Please add yourself to this bug.  To solve the issue, you should;
- shut down your SBS
- delete the cache directory
- power off your Controller
- startup the server 
- power up the Controller while holding down the + key (this will do a Factory Reset
- walk through the setup on controller

If you still have problems, please call support
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The bug I was trying (but failed to) describe is the message you get AFTER upgrading to 7.4

see attached.

Created attachment 5995 [details]
upgrade image

This is what I see, every time I hard power cycle the Controller.  Remove battery and place it back in.

*** Bug 14469 has been marked as a duplicate of this bug. ***

Same problem here - seeing the upgrade welcome screen every time I boot SBC.
Using the official 7.4.1 - r28947.

7.4.x milestone is in the past

don't think this is valid for >=7.5