Files created with a trial version can only be opened on the same machine that created them.
They may also be locked to the same build of Archicad they were created in - I am not sure.
If the file you are trying to open was created on that machine, then that must be the case.
However you should be able to open a new file in demo mode.
One of the forum moderators. Versions 6.5 to 25 Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10 Dell Precision 3510 - i7 6820HQ @ 2.70GHz, 16GB RAM, AMD FirePro W5130M, Windows 10
Thank you very much for your question and I am very sorry about the issue!
I have never seen such issue before. I’m wondering between the trial period and the update, are there any other changes to the computer? Also, have you tried to completely uninstall and reinstall Archicad?
IIRC Trial versions are very picky. On install or first launch they do something to lock itself so that if you try to uninstall and reinstall then the project that you were using for a trial will be locked out which also happens when the trial ends. Trial projects can only be opened by the trial installation that created them. You can't even open the trial project on another machine even if it has a full AC license.
My guess in this case is that since you"updated" the trial then that installation became invalid and will not open and I would also guess that uninstalling and reinstalling will not work also.
eduardo rolón AIA NCARB Another of the forum moderators. Macbook Pro 2.4 i9 32GB ram OS X 10.XX latest AC25 US/INT -> AC08