16x MapFix v1.1.4.0
FS25 16x Map Fix – the root cause + a tool to fix it
Why do 16x (and larger) maps in Farming Simulator 25 crash with an “allocReg” error
or get stuck at “100% Shader Compilation”? Here is the complete diagnosis as well as a tool
that enables loading and synchronization in multiplayer on normal hardware.
Important:
Do you like the tool?
You can support its development on Ko-fi – please mention “16x Map Fix” so I know what to work on next.
Diagnosed on a dedicated server and a client with 16 GB of RAM, both running the same 16x map.
The tool reduced the “allocReg” errors on a genuine 16x map from 878,987 to 0, making it playable in multiplayer.
In short (TL;DR),
the “allocReg” crash is actually caused by two different problems that look identical:
Cause Solution
Single-player Memory requirements – a 16x map requires approximately 20–32 GB during the initial compilation of the density data (density maps); 16 GB is insufficient.
A large swap file (48 GB+) + DX11 → the original, unmodified map loads. Multiplayer
A tile registry with a fixed capacity in the density map synchronization module works by reducing the writable density layer of the map to 8192 pixels for 16384px density maps – see tool below.
Proof that it’s not a RAM issue in multiplayer: A dedicated server with 262 GB of RAM still produced the same 3014 “allocReg” errors. More RAM or a larger page file doesn’t help in multiplayer – only fewer tiles solve the problem.
The cause in detail.
The overflowing layers (fruits, soil, weeds, info layer) are the game’s writable “terrain detail” density maps—you plow, sow, and harvest within them, everywhere, even outside the visible area, and the server monitors the entire map. Writable data cannot use “virtual texturing” (where only visible, read-only tiles are streamed); therefore, these layers must reside entirely in memory and be registered. Their resource requirements scale with the map area: 16x means 16 times the number of tiles. In single-player mode, the client loads its own pre-compiled .gdm files; the only bottleneck is the brief spike in memory usage during the initial compilation, which is handled by a sufficiently large page file.
In multiplayer mode, the server transmits density maps to each joining client, which recompiles them live via the fixed-size tile registry (TiledBitmapOperationCompiler). A density of 16384 pixels leads to an overflow—and thus to thousands of “allocReg” operations. This represents a hard capacity limit that is independent of RAM; this is precisely why even servers with 262 GB of RAM fail, and why the effective upper limit of GIANTS for multiplayer mode is four times the standard size (4x): A 4x map is the largest area whose writable density fits into both the registry and the synchronization per connection.
The tool
tool/mapfix.py + tool/Optimize-Map.bat (Windows Drag & Drop). It scales down any oversized density or information layer (16384 pixels, power of two) of a map to the engine-safe 8192 pixels – precisely the resolution at which functioning 4x maps are delivered. Field and crop information is preserved (decoding → resampling via “nearest neighbor” → re-encoding; verified as 99.9% pixel-identical, crop coverage unchanged). Elevation maps and terrain geometry (dem.png, raster with 2ⁿ+1 points) are recognized based on their size (not a power of two) and are not altered.
Application
Drag your map ZIP file into the `Optimize-Map.bat` folder (requires Python 3 – Pillow will be installed automatically).
A file with the suffix `_fixed.zip` will be created in the same folder – your original file remains unchanged.
Upload the corrected map to your server, start a new game (important: old save games contain the old density revision), and join the game.
Includes `grleconvert` (MIT license) for converting between .gdm/.grle and PNG. Supports 16x and 32x maps; output is always in the safe 8192-pixel format.
Note regarding multiplayer (GIANTS autosave).
Even with a corrected graphics card, the GIANTS Dedicated Server performs a blocking autosave (`auto_save_interval`, default: 10 minutes). With large graphics cards, this save process stalls the main thread for so long that the connection to the client can drop at that exact moment (“connection lost”), while the server itself remains online. Increase the value for `auto_save_interval` in the `dedicatedServerConfig.xml` (e.g., to 30–60) to minimize this problem.
Additional mod: Auto VRAM Optimizer
A small, standalone mod that raises the texture streaming limit in FS25 (approximately 4 GB by default) to the actual VRAM of your graphics card. This results in smoother loading and fewer pop-ins for all graphics cards with more than 4 GB of VRAM – not just 16x cards.
