Yes, I only get this error when doing the software update. It also occurs in safe mode. I have not gotten an update prompt. I just received the tablet and was checking to see if any updates were available.The device is on Kitkat 4.4.2. The build number os 17.1.D.1.136. This is the second SGP561 I have had and they both got this DM session error when doing the software update.
I purchased this Z2 on Ebay & got it a week ago. As far as I can tell, it has no mods applied, no custom ROM, or such. The software version is SGP561_1278-4455_17.1.D.136_1291-7765_R1A_user
Same issue here with an xperia z3v. No alterations of any kind. One month with me and purchase brand new. Build Number 23.0.E.1.44
Nobody in other forums know about this issue.
Hopefully, the original seller will.
Waiting for the solution........................
No resets. And except for being unable to do the software update, the tablet is working well. I should add that it doesn't have a sim chip. I am using it as wifi only.