Wall of red errors in the log on launch

Open Player.log at %USERPROFILE%/AppData/LocalLow/Ludeon Studios/RimWorld by Ludeon Studios/Player.log and find the line naming the failing mod. The usual cause is a missing framework — subscribe to Harmony and HugsLib on the Steam Workshop, enable them at the top of the mod list right under Core, and run RimPy's auto-sort.

A mod shows as active but nothing from it appears in the game

The mod failed during load, almost always from a missing dependency or an XML error in its defs. Check Player.log for the mod's name, enable every framework it lists (Harmony, HugsLib, JecsTools), then re-enable the mod and reload.

The mod list marks my mod as incompatible with this game version

RimWorld and mods each carry a version tag (for example 1.5). Update the mod through the Steam Workshop if one exists, or switch RimWorld back to the version the mod targets using Steam > Properties > Betas. Older abandoned mods may simply not work on the current version.

"Mod not loaded" / XML error for one specific mod

This is a broken or incomplete XML def in that mod. Unsubscribe and resubscribe on Steam (or re-download the ZIP and re-copy the folder for a manual mod), then enable it again. If it still errors, the mod is likely abandoned for your game version — drop it.

Two mods conflict and one overrides the other

When two mods patch the same def, load order decides the winner. Run RimPy's auto-sort, and check the mod pages for a compatibility patch. If none exists, keep only one of the conflicting mods.

The game is really slow with my mod list

Load time, map loading, and ticks-per-second all get worse as the mod count grows. Disable mods you do not actually use, and consider a performance mod like RocketMan or Performance Fish. The reliable fix is cutting heavy mods and re-adding them in small batches.

A mod won't load because it needs a DLC I don't own

The mod requires Royalty, Ideology, Biotech, or Anomaly — its Workshop description says which. Either buy and enable the DLC, or skip the mod. Some DLC-gated mods still start with warnings but lose their DLC-only content.

My save won't load after I removed a mod

The save still references defs from the removed mod. Re-enable that mod (or a compatible successor) to get the save loading, remove the mod's items in-game, then disable it again. Back up your Saves folder (Documents/Ludeon Studios/RimWorld by Ludeon Studios/Saves) before changing mod lists mid-colony.

I subscribed on the Workshop but the mod never shows up in game

Restart Steam so the Workshop download registers, then relaunch RimWorld and check the Mods menu. Confirm the subscription is for RimWorld specifically. If it still doesn't appear, unsubscribe and resubscribe, or install that mod manually into the Mods folder.

My mod list reset / mods got disabled after a game update

Game updates disable mods flagged for the old version. Re-enable them in the Mods menu, then run RimPy's sort. If you saved a mod list in RimPy, restore that profile to get everything back at once.

Errors keep mentioning Harmony, or a mod says Harmony isn't loaded

Subscribe to the official Harmony mod on the Steam Workshop and place it first in the active list, directly under Core, so it loads before every mod that needs it. RimPy's auto-sort does this automatically; avoid mods that bundle their own conflicting copy of Harmony.

The game crashes to desktop when I enable a certain mod

Disable that mod and test — a hard crash usually points at one mod or a mod pair. Enable your list in small batches until the culprit is found, and check Player.log to see which mod was loading last.

Mod content (pawns, items, factions) is missing in my colony

If the mod loaded without red errors, its content only spawns in worlds and colonies created after it was enabled — start a new game to get it. If it's a failed-load issue, fix the dependency or XML error first, then start fresh.

I have two copies of the same mod — one Workshop, one manual

Running both copies causes duplicate-def errors and conflicts. Keep one: unsubscribe from the Workshop copy while you test the manual one, or delete the manual folder from the Mods directory, then reload the game.

A mod shows a yellow warning triangle in the list

A yellow triangle means RimWorld suspects the mod is outdated or otherwise problematic for your version. Hover over it for the reason and check for an update. If it loads clean you can ignore it — but treat red errors, which are load failures, as blocking.

The first launch after adding mods takes forever

That first load recompiles the C# code of new mods (the "Compiling mod code" step) and is always slower; later launches are faster. If every launch is slow, the list is simply too big — trim it or rebuild it in RimPy.

I can't find the Mods folder to install manually

In Steam, right-click RimWorld > Manage > Browse local files, then open the Mods folder inside the game directory. If it is missing, launch the game once to create it. A manual mod must sit as one subfolder containing About/About.xml.

Red errors only happen in my existing save, not in new games

Your save references defs from mods that are no longer active or that changed. Load the save, let the game warn you, and remove the affected items. If the save is broken beyond use, the mod list changed — re-add the missing mod or start a new colony.

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