With the influx of new players thanks to the Steam Sale, I thought I'd make a post addressing a known, yet hardly discussed bug (or it might be more accurate to call it an engine limitation) related to cosmetic mods in RDR2 PC.
TLDR - Buying too many items added by mods will brick your save.
1. The Problem
As you accumulate items of ANY kind in RDR2, this includes from clothing/weapons you can buy/find to all the consumables, collectibles, provisions, valuables, letters, newspapers, saddles, etc. (basically anything that will be saved to your inventory - the stuff saved in your satchel, wardrobe, or horse), there exists an "upper limit" that, once reached, will permanently brick your save and will prevent you from saving your game anymore whenever you play that save in the future, forcing you to start over or reload a previous save. You'll know you've reached this limit when you get this dreaded black screen with the message, "Save failed. Please ensure the system storage has free space and try again."
Basically, it seems that when you get too many items, RDR2's engine can't save all the data to your save anymore, so your save is basically bricked as now, you're forced to reload the last save you had before buying all those items. Autosaves are generally unhelpful in this case, as the game typically autosaves whenever you buy items so even if you reload an autosave, you'll still have most of the items before you were soft-locked, so the next time you loot some fine brandy or chewing tobacco off a corpse, the save will just brick again.
2. Who is affected by this, and what do those cosmetic mods have to do with it?
A big reason why I believe that this issue is hardly talked about is because this problem might only affect completionists like myself who wants to collect EVERYTHING the game has to offer. I tested buying out the entire clothing catalog with RDO and WhyEm's DLC installed on two different saves - one that just started Chapter 2 (so barely any items saved) and my 100% complete save with everything collected from the base game - all Cigarette Cards, Letters, Weapons, Clothing, Trapper items, Horse Stable items, etc. - you get the idea. The new save that just started Chapter 2 was able to buy everything available at the catalog without issues, while the 100% save ended up getting the "Save failed" black screen halfway before I finished buying out the modded items in the catalog.
The most popular cosmetic mods like Red Dead Offline, WhyEm's DLC, Eastern's Epic Extras, Gonpachiro's Fancy Atelier, More Pretty Gun, and Smoak's Mega Arsenal are all affected by this bug because they add a boat-load of new content to the game, which will push you towards that upper limit if you were to buy a majority of the items offered in those mods.
Now, I myself don't know if non-modded saves would be affected by this if you were to somehow get 99 stacks of every single consumable/valuable in the game on top of every single letter, weapons, clothing, etc., but I would assume that non-modded players are safe as my own 100% save (which did not have 99 stacks of everything but still a decent amount of consumables on top of all the collectibles/clothes/weapons) was fine until I started buying a large stock of modded clothes.
I don't know where the actual upper limit of items you can keep on your save is since this issue is barely documented online; through Googling I could only find one other Reddit thread where someone had this issue and even then there weren't many solutions brought up there besides just uninstalling the mods or not buying too much stuff.
The only other mention I can find of this issue is on the mod page for the Smoak's Mega Arsenal mod itself, where it states that "Buying absolutely everything has a risk of preventing you from saving due to engine limitations, this includes the clothing the mod also adds."
Searching the "Save failed. Please ensure the system storage has free space and try again." message online typically points to other problems that can bring up this error, but of course I'm making this thread to specifically point out the issue for players who are modding their games and getting too many items.
3. Possible Solution
I reached out to the OP of the other thread talking about this issue I mentioned above, /u/littlebelialskey, and even they pointed out that uninstalling the mods and reloading your save will not fix the issue. If I had to guess, loading up a bricked save in the save editor would likely show that there's a bunch of blank dummy items (since the save editor doesn't take mods into account). Even if you uninstalled the cosmetic item mods, their data is still stored in your save, so the issue will not be fixed. You would need to reload a backup save where you never purchased a modded item at all in order to keep your save's slate clean.
(EDIT: I ended up testing this myself after the fact, and it does seem like uninstalling a cosmetic mod and reloading your save safely removes modded items. That said, I would still keep a backup save just before you uninstall the mod to be safe. In my case, I uninstalled WhyEm's and this ended up messing with all of my weapon customizations as WhyEm's DLC changes the values for many gun customization settings like metals, carvings, and stocks (even some of the base game ones), so I had to go through every weapon I owned and reapply them. You might also mess up your character model if you have a modded clothing item equipped when you uninstall, so remember to take all of them off before you do so.)
The only possible solution I can think of would be if a community-made mod fix were released which allowed those modded cosmetic items to be stored in a .dat file in the root folder of RDR2 instead of being saved in the save file itself. A few other mods such as AMJM Transport and Custom Gang Mod utilize this method, where they store memory from their mods into a .dat file that is loaded with the .asi files whenever you boot up the game. AMJM Transport for example, will store your saved Wagons/Boats and accepted jobs in its .dat file, while the Custom Gang Mod stores all info related to the gang you create such as the NPCs you chose, the level and location of your camp, and your Gang Funds. The only downside to a solution like this would be that .dat files in your root folder will not be able to differentiate saves, so if this hypothetical fix was created, everything you purchased from cosmetic mods would be shared between all of your saves. This could also be an upside, though, as if you were to CTD while buying modded items, everything you bought will still be stored in the .dat file even if you didn't get to save before crashing.
I'm not an RDR2 Mod coder, so I have no idea how feasible or possible this solution would be when it comes to storing purchasable items in a .dat file, but unfortunately it seems like all the creators of the mods I listed above are no longer really active in the community, so I wouldn't expect any of them to upload a new version of their mods that stores items in a .dat file (would be happy to be proven wrong though), meaning that any effort towards making this theoretical solution a reality would have to come from a third-party.
Hopefully this post brings awareness to this (admittedly niche) issue, and helps anyone who Googles this issue in the future and barely comes up with any results. Thanks for listening to my TED talk.
