Setting up UOFiddler

1. Download the latest release of UOFiddler.
2. Settings > Path Settings → paste your Ultima folder path → click Reload paths (list should populate with .mul, .idx, and .uop files).
3. Setting > Options > Output Path → set to a new local OUTPUT folder (this is where the .mul and .uop files will be written).
4. Plugins > Manage → enable MassImportPlugin.
5. Plugins > Manage → enable UOPpacker.

Patching using UOFiddler

1. The ultima_online_mods folder includes 00_ART_MODS_MassImport.xml (a list of item IDs and file paths for the modded art). Edit the file paths with a global “replace all” to match your system paths, or generate a custom XML using 00_mod_selector.py.
2. Plugins > MassImport → Load XML → select 00_ART_MODS_MassImport.xml from the downloaded mods folder (loads replacement art files).
3. Enable DirectSave, then click Start (may take ~1 minute).
4. Your OUTPUT folder will now contain the modded .mul files.
5. UOFiddler → UOP Packer → paste the OUTPUT folder path → turn ON Pack MUL to UOP → Start.
6. Close UOFiddler. Copy the .mul, .idx, and .uop files from OUTPUT into your Ultima folder, overwriting existing files.
7. Installation complete — launch Ultima Online.
8. If your shard updates later, patch using their updater (verify), then repeat the MassImport process in UOFiddler.

Patching Troubleshooting

• Terrain textures look mismatched/random in-game: This usually means a shard patch updated over the modded files. Re-apply mods with MassImport after updating to the shard’s latest.
• MassImport crashes/freezes (>2 minutes): Your source .mul may be corrupted. Restore backup .mul files or delete them and verify via your shard’s launcher to download fresh unmodded versions, then re-run MassImport. This can happen after shard updates.
• After a shard update, the client crashes with “System.OutOfMemoryException: Array dimensions exceeded supported range.” referencing ArtLoader: delete the recently updated .mul or .uop files in the client directory, verify again with the shard launcher to fetch clean copies, confirm the client launches, then run MassImport on top using UOFiddler.

- OR - Install using Varan Mulpatcher ( OLD METHOD )

• alternatively can install using Mulpatcher | Alternate Download
• Settings > Art > set the mul paths : Art.mul path ( Ultima directory ) and artidx.mul . click LOAD . repeat for Gumps and Textures .
• Features > Autopatch > select the mod txt file( 00_ART_ALL_ART_S.txt ) and set Art(S) as category dropdown > hit START .
• Repeat Autopatch process for the following mod txt files :
• 00_UI_ALL_GUMP.txt ( Gumps ) , 00_ENV_ALL_TEX.txt ( Textures ) , 00_ENV_ALL_ART_M.txt ( Art (M) ) , 00_ENV_ALL_ART_S.txt ( Art (S) )
• Settings > Save the Art mul to the Ultima directory ( Ultima directory ) . repeat for Gumps and Textures .

INSTALL NOTES EXPANDED

Additional Guides and Mods hosted by Gaechti : - http://www.burningsheep.ch/finished.html - http://www.burningsheep.ch/howtoUOP.html

Launch Client and play !

• follow your Servers news for updates and patches .
• when a new patch occurs , in the launcher click the verify button which will get latest
• then reapply art mods using the process above.

Additional Guides

Gaechti :

http://www.burningsheep.ch/finished.html

https://forums.uooutlands.com/index.php?threads/gaechtis-ultima-online-patches-tree-stump-better-reags-and-more.838/