Can't upgrade to v1903 from v1809

First, it appears your laptop is officially only supported to Win 8.1. Formally, from an engineering specification viewpoint, that's all it's guaranteed to support.

Granted, millions of users upgrade to Win 10 with older PCs not verified to work with it, taking the risk of incompatibility (esp. when upgrading manually).

Second, experience shows that a few PCs, when upgraded from one Win 10 build to another, find that there then is some technical issue. For example, the new set of drivers delivered with the new build - including low level drivers intrinsic to Windows- may demonstrate an incompatibility.

Third, MS has tried to put in place, via Windows Update, a level of protection to prevent users inappropriately upgrading where this could cause problems.

Fourth, it's an Insider build. So don't expect perfection.

Now from a user perspective, one could well imagine this is necessarily imperfect and incomplete - indeed the message you show might reflect that. Or it might simply mean things have moved on.

In your case, I would assume you could try downloading the relevant iso, and try upgrading manually. This might circumvent the restriction. I would regard that as purely experimental, and you should ensure you have a full disk image (as is so often advocated here as a matter of routine) e.g. Macrium Reflect (free) before attempting the upgrade.

Also make sure your BIOS is fully up to date.

Consider this: if a PC is initially released with Win 10, and Win 10 evolves over, say, 15 years, would it necessarily be the case that all such PCs would still be supported? I believe users have yet to learn that indefinite upgrades are not guaranteed.

I got the same message on one of my laptops, a 4 core 64 bit 2 ghz intel cpu with 16 gig of ram, so I closed the message ..... And eventually after about 2 minutes the update continued and installed!
But that was when the problems revealed themselves: The "Settings" menu was a mess, and the "Updates" section was completely unusable. Everything else on a cursory examination seemed to be working, but without "Settings" working correctly the installation was useless, so I rolled back to 1809.
Microsoft posted a second message saying they would look into the problems and inform me when a fix was available, I won't hold my breath waiting?

I think these are driver checks... which is a good thing.. the unabashed may go the ISO route and find it works.. (great!) but I think MS needs to ensure that, the tested drivers distributed, work on the hardware it's being installed on... IHMO (as always.. :) )

You're welcome.. copyright fees of course..
- if you use it, could add supporting links I guess..

Here's an odd thought.. with 1903, Home users will not be forced to apply feature upgrades until EOL of 1903 (unless MS's changes this again... clearly their roll-out strategy seems to be in panic/reactive mode).

Now, if many choose to opt not to upgrade, then MS gets less feedback on failures.
Therefore, 18 months + on from 1903, you can expect a larger proportion of problems and failures- a peak- as more will have changed with having missed two builds.

In the instances cited in this thread, it will be interesting to see if MS is able to monitor the numbers experiencing this automatically, and see a peak- and respond. Or will they simply say- as they could well be entitled to- there was no guarantee and you're using your PC out of specification- and received a clear message about this.

Or will they simply have to bow to bad publicity and public pressure?

Whatever the outcome, it can be fairly said MS has failed to prepare the ground for users to accept their PCs cannot and will not be supported as a legacy upgrade when the manufacturers of said PCs only support drivers for, say, Win 7 or 8. By simply defining the upgrade paths in terms of what Windows licenses you have without more specific reference to hardware and manufacturer support, MS seems to have failed to prepare the marketplace for the inevitable.

It becomes a matter of license terms + user expectation vs user experience of being able to upgrade a PC to Win 10 that was never designed to run it.