I tried several times to update to 1903 and every time i had the same result.
I tried updating from Windows Update. Didn't work.
I tried updating from a USB Stick. Didn't work.
I tried updating from a directory on the HDD. Didn't work.
At some point in all this I uninstalled my Antivirus.
Tried the other usual tricks like swearing at it, giving it a really hard stare and as a last resort clicking the mouse over and over again. Didn't work either, surprisingly!
I read a few articles about the update and what had and had not worked for others. Removal of USBs seemed to be high on the list for troubleshooting. I use a wireless mouse which has a USB. I have never been a fan of track pads, I'm old school and like a proper mouse.
I unplugged it and turned the trackpad on to start again.
I ran Windows Update and walked away. Then I left it overnight to get on with it.
The next day I checked it. It had worked.
It was showing 1903 in Settings --> System --> About.
I had thought that removing USBs referred to just memory sticks and connections to other devices, but no, it meant everything.
So my recommendation for updating to the newest version of windows 10 on your laptop is remove EVERYTHING that is connected by USB. USB sticks - remove! Mobile phones - Remove! Wireless Mice - REMOVE! Wireless Keyboard - Remove! Printers, WiFi Dongles, Bluetooth dongles - remove remove remove.
I did not have this with my desktop, but the motherboard is newer. However if you have issues with updates on a desktop try the same thing.