It's very unlikely this has anything to do with the patch specifically.
What can happen is that sometimes a new update will trigger an anti-virus to scan your OOTP data files and that will corrupt your saved game files if the anti-virus returns a false positive.
For anti-virus, anti-malware, disk cleaner programs etc. it's a good idea to add OOTP to their whitelist and exclude OOTP and its data folders from any disk cleaners or similar programs. This is a pretty important step, as it's probably where 95% of the issues with league corruption come from. Basically, any programs that can change or delete files on their own, without asking you about it, you'll want to have them steer clear of any OOTP files and folders.
You may be able to restore from the autosave function. Instructions on doing that follow:
To restore from the automatic backup, do the following:
1) Open the game and on the start screen, click on Settings
2) Now click on the tab "Troubleshooting".
3) Click "Open folder containing saved games".
4) Now open up the league folder you're wanting to restore.
5) Then select all of the .dat files in the folder and back them up (just in case) by copying them to a temporary folder or creating a zipped file with them
6) Open the folder called "auto-save".
7) In there, select all of the ".dat" files and copy them to the league folder (the parent of the current folder) overwriting all of the ".dat" files in the league folder.
8) Now start the game and load your league.
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