> Finally I just unchecked the plugin for Book Covers Skyrim and that finally worked. I can now get in to the chest and get the book and read it. But... it also means my save now gives the error "This relies on content no longer available..." so will my game be screwed now? <
Don't do that because,
Now that you've un-installed your mod, there is no way your save game is going to work properly.
But, you can still play the game as normal but that mod will no longer be active. When you save and reload the game, normally you won't see that warning again.( Can you check it for me please ????)***
if you reload your save, and you get the message again, you are going to have to start a new game. (because maybe later you will have problems with that...)
Really the only thing you can do wrong is uninstalling mods, particularly the mod in which your same game was placed. Which added key elements in your current save game.
Save games remember everything... so the more you add/remove from them (mods) the higher the chance it breaks stuff.
You can always safely run Weather, Lighting and Texture mods, as well as weapons, armors, skins, skeletons, etc... they contribute a great deal to the experience...
just take care with things that add stuff (buildings, quests, skills, etc) to the game... they have potential to break stuff if not used (uninstalled in this case) or created well.
In your game, if you want to avoid problems, play through on vanilla with no mods until after Helgen, then add one or two mods or other changes at a time, run BOSS (if you added mods) and play a bit to check stability
before adding one or two more.
Once you get a stable game with the mods you want, do not alter the game until you are tired of your character and are ready to start over.
Also, disabling autosaves and quick save will minimize corrupt save problems.
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From the Bethesda document, “Skyrim Mod Troubleshooting: Best Practices”:
"When you play Skyrim with a mod, in most cases, the new data for the mod will be written into any new saved games you create.
For example, if you play Skyrim with Mod X and create a save, the next time you load that save, the game will expect Mod X to also be loaded.
If you no longer want to play Skyrim with Mod X, it is best to unload Mod X (by unchecking the plugin under Data Files in your Skyrim launcher) and loading a save that does not require Mod X, usually an older save or a backed up save."
The short version is, “Never continue with a save once a mod it relies upon has been removed.”
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However, although this is good advice, there may be occasions when it is inconvenient to heed it.
There are many mods that modify the game in a way that does not immediately change when the mod is uninstalled, a more thorough cleaning must be attempted.
These modifications can cause CTDs and freezes (and other issues) if they remain in the world space after the mod has been uninstalled.
These advanced cleaning steps will force exterior and interior cells to reset, despawning and respawning almost all actors in the game, among other things.
To make sure almost all cells reset, its is necessary to wait for 31 days. Some cells will never reset, as they are flagged as "Never Resets" by Bethesda.
These mostly include player homes and other important locations.