I found an exit to this problem:
1) Identifying the problem:> FAST2 crashes when checking MODs at the beginning of the program.
2) Preparing the solution:> Make a copy of the FAST2 installation folder.
3) Server's MODs:> Go to the SteamCMD folder (C: \ SteamCMD \ steamapps \ workshop \ content \ 107410) in our case here. Note that each mod is indicated with the Workshop ID (example ACE3 for ArmA3 the Workshop ID is 463939057). You will have to test all ID's one by one in order to find out which mod was taken from the workshop.
5) To facilitate:> https://steamcommunity.com/sharedfiles/filedetails/?id=463939057
you only have to change the number at the end of this address, which is already on the MOD page.
6) Download the latest version of the program. Unzip it to a different folder and run the FAST2 configuration as the original installation of your server.
NOTE: Do not run the SteamCMD installation (since it is already installed)
7) The improvised solution:> in item 5 support test, you should already have located which mod's are no longer part of the workshop, so, you will run this new installation, the server's mod's will be on the tab LOCAL MOD's. Go to the problematic mod and delete it.
8 ) Close this improvised version of the FAST2 installation and run the version in which it was previously installed. If you have performed the correct step by step, the program will not lock again.
9) Tip to avoid new problems:> go to settings tab and uncheck "Check for Steam Mod Updates on Launch" and "Auto Update FAST on Launch".
I hope it helped you.