Follow the next steps:

1. Be sure that all your DRIVERS are UPDATED, this seems to solve the issues for some users.

2. UNSUBSCRIBE all the MODs from the Mod Manager. Check it a couple of times at least, because some mods insist on staying there. Occasionally, some mods contents remain once unsubscribed and keep causing conflicts, to avoid this DELETE all the folders inside:
\Steam\steamapps\workshop\content\214950

3. DELETE the next folders:
C:\Users\{YourUser}\AppData\Roaming\The Creative Assembly\Rome2\ui_cache
C:\Users\{YourUser}\AppData\Roaming\The Creative Assembly\Rome2\logs

4. Verify Integrity Of Game Files: in the Steam Library right click on Total War Rome 2, select Properties and check the option in the "Local Files" tab.

Or make a CLEAN INSTALLATION of the game, which is the most RECOMMENDED option. In this case FIRST DELETE the folder:
C:\Users\{YourUser}\AppData\Roaming\The Creative Assembly\Rome2\
and be sure that there are not remaining files at:
\Steam\steamapps\common\Total War Rome II\

5. INSTALL the 3 vcredist .exe packages that you can find in the next route:
\Steam\steamapps\common\Total War Rome II\redist
and the DXSETUP.exe at:
\Steam\steamapps\common\Total War Rome II\redist\directx
To be sure that you have all the libraries that the game requires.

6. SUBSCRIBE only to the Para Bellum mods.

7. CONFIGURE all the Para Bellum mods AS DETAILED in the descriptions of each part: some parts include SPECIFIC INSTRUCTIONS that are necessary to apply in order to make the mod work without issues.


Other IMPORTANT TIPS:

- The saved games can get corrupted randomly, so save the campaign frequently and in different files. If you see that your saved game file is lower in size than the previous ones, this is a clear indication that at some point it has been corrupted, as the saved games files size increases as your game advances including more data with it.

- Don´t active/deactivate mods during your campaign.

- Avoid minimizing during the game.

- Lower the graphics: some Para Bellum parts can be GPU intensive, and as Rome 2 engine doesn't address more than 3GB vram, when that limit is exceeded, it will start using system ram to handle additional textures data, which is much slower than the vram, and may bottleneck the cpu with the consequent crashes.

Also you can try to uncheck the Unlimited Video Memory option, and optionally the Shader Model 4.1 of the Graphics Options menu (you won´t notice a downgrade with this option).

If you use Para Bellum - Effects I recommend the Lite movie.pack version that you can find in this mod description, as includes blood but without the particle effects that can affect the performance significantly on some rigs.