Strange sh ver message after an IOS upgrade of a switch 3850

[alcione009]

By upgrading IOS of a cisco switch WS-C3850-48U to version 16.6.5, at one point of the procedure the switch reloaded itself and then, once up and upgraded and perfectly running, I got the following result from the show ver:

Myswitch  uptime is 1 week, 21 hours, 50 minutes
Uptime for this control processor is 1 week, 21 hours, 58 minutes
System returned to ROM by Power Failure or Unknown at 06:06:40 CEST Mon Jun 27 2016
System restarted at 18:30:38 CET Wed Mar 25 2020
System image file is "flash:packages.conf"
Last reload reason: Power Failure or Unknown

Is it correct what I highlighted with bold characters ? Why the switch says by power failure or unknown ?

Please note that yesterday I relaoded the switch with the reload command and it correctly showed:
System returned to ROM by Reload Command at 18:32:40 CEST Wed Apr 1 2020

[balaji.bandi]

There are couple of bugs related to this, I was in impression this was fixed on your version you upgraded, but looks have not.

If this is not effecting any production enviroment, and accepatable the message, continue with the stable version.

if that is worrying bit, raise a TAC case for them to investigate further and let you know when the fix available or suggest you alternative.

[alcione009]

Thank you very much for your answer balaji. I add some details that I, and excuse me, forgot to provide previously. This is a stack composed by 3 switch. We were upgrading IOS from version 03.06.05E to version 16.6.5 and we succeded. I wrote this question in the community because I found very strange the message, since no power failure occurred and also the date is not right (2016!):

System returned to ROM by Power Failure or Unknown at 06:06:40 CEST Mon Jun 27 2016

By the way I can also say the equipment is still working fine after the IOS upgrade.

[Leo Laohoo · Accepted solution]

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@alcione009 wrote:

We were upgrading IOS from version 03.06.05E to version 16.6.5

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I know the reason why and the information (above) is vital.  

Upgrading from 3.X.X to 16.X.X means a mandatory ROMMON/microcode upgrade. 

This means during the "reload" phase, the switch is really doing a complete reboot (like someone pulling the power cord) and the "sh version" output reflects.