Anyone had the White screen of death on exiting a session, today saved and exit driver. Just a plain blank screen, waited 10 mins still nothing. Ctrl Alt Del and forced exit. I think that after many edits of route and overwrites of a session it becomes corrupted. No great drama need to build and refresh a session anyway. Sort out the places where its not practical on a large route.
I've seen that before.

Basically, Trainz is busy saving your edits to your routes and sessions and your computer isn't refreshing the display at the same time causing the display to become white when you click on it. Unfortunately, you may have corrupted your route or session if you canceled the process because the file hasn't been completely written to disk. The larger the route, the longer this process takes. You are now going to have to run a DBR or an EDBR to clean up your database. Hopefully you have a backup of the route or session you had open when you exited the program.

You might want to try these:

1) Ensure you have enough disk space.

Programs such as Trainz swap stuff from memory to disk. This includes all kinds of temporary files, and other program data. If the disk space is low, then this process takes a lot longer to complete because the operating system is swapping around to fit the data.

2) When was the last time you defragmented your hard drive if it's a regular spinning disk?

Defragging your disks helps a lot with Trainz. The files are opened and closed and written constantly to disk. By defragmenting the disk, this speeds up the read/write process making the saving of files much faster.

3) If you are using an SSD, you definitely need to TRIM the drive. With Windows 10 and Windows 11, you can do this right through the built-in Defrag utility. Even though the program says defrag, it automatically switches to TRIM for SSD drives. TRIM doesn't help with speed but it ensures that your disk has marked empty cells for reuse.

4) You should run some disk diagnostics. A slow save or read can be a sign of a failing disk!

Check your hard drive for errors, and most importantly backup your data. This is very important with SSDs because when an SSD fails, it may lose performance initially but will fail suddenly with no recourse or ability to recover your data.
DBR I do after every exit, habit I got into from 2006 days. Did notice after looking for missing dependencies and hopefully downloading some fixes. My route and session had big red question marks in the menu pictures. So something went awry. Had a locomotive lose its tender for some reason.
Anyhow another edit of route done, and session created. With all new consists. Plus I always do a CDP whenever I update things. Another habit from 2006 days, when routes would vanish.
Run a SSD, so I have not done a trim of anything. Still on Windows 10.
I am going to upload this route to 22 and see what happens, Although downloading any content again could be a pain, as I dont think any downloaded content goes over to the newer version. When I went from TANE to 19 with this route alot of stuff I had to re download.
I recommend running TRIM on your SSD. It cleans up the disk and marks empty cells as available for reuse and reduces wear on the drive.

What is SSD TRIM, why is it useful, and how to check whether it is turned on (

The procedure takes a few minutes.

A red ! means you have faulty assets. You should check for faulty assets in Content Manager. Some may be false errors caused by the crash and database repair. Right-click on the faulty assets and view errors and warnings. You should see zero errors and zero warnings. You need to exit the screen in Content Manager and check again to refresh. If you have any errors left, those assets are most likely corrupted and need to be redownloaded or installed.