I have a Clickonce app from Visual Studio 2015 SP3 that is published to the network server and used in-house only. The program works just fine when launched from Visual Studio. It runs just fine on a Windows machine that does not have the 1803 update. But once a machine updates to 1803, the application no longer starts. I get the "Checking for updates..." window then nothing. On a fresh install, I usually get the Smartscreen telling me the program may be dangerous. It doesn't get that far.
I've created the Clickonce from a computer with the 1803 update and the problem still exists.
I've disconnected the machine from the network. The application starts but then has no database access and it needs the database. It's also written to hide buttons that would use the database to prevent users from trying to do things that require it.
I found a workaround (third paragraph) at https://social.technet.microsoft.com/Forums/en-US/7cbd16f5-526e-4b0b-a186-3ebf41b7b349/smartscreen-prompt-does-not-show-for-clickonce-app-since-windows-10-update-1803?forum=win10itprogeneral. When I start the application from the directory mentioned, I get the Smartscreen and can tell it to run anyway. Every time I click the desktop icon, it works just fine.
If a new release is published, the new release is downloaded and the program updated, but the Smartscreen no longer appears and the application never starts.
So somewhere between installing the latest update and the Smartscreen, this is failing. Anyone else experiencing this and have an idea as to why?
Yes, frustratingly I also experienced this today. Presumably a security update that they'll release another patch for given this is quite a pain for developers and users of small business apps.
Rather than disable Defender or SmartScreen I chose to add my deployment website to the Trusted Sites in Internet Explorer and that then re-instated the warning dialog and my app updated and ran as before.
Really annoying given the nature of the issue and how long it took to figure out, but at the same time I had to use IE today, which is a rare event nowadays.
This works for me...Warn doesnt warn anymore...
It appears as though some subsequent Windows Updates have fixed the issue on several of our PC's that were previously experiencing the issue.
Check for the updates listed here. https://www.catalog.update.microsoft.com/Search.aspx?q=KB4338548
Running winver.exe will show you which build you have.
After running in the same problem, I just found that my application was going to halt after a stupid uncaught exception.
Despite the fact that the image below is in Portuguese, Event Viewer shows the right error cause.
In my case, was a corrupted settings file!
来源：https://stackoverflow.com/questions/50379742/clickonce-app-doesnt-start-with-windows-1803