The September 2026 Update, for People Who Run Servers
The September 2026 update went live on 16 September 2026 at 15:00 GMT. The headline is 64-bit binaries on Windows, and the practical effect is that the crash people have been reporting for years on large addon collections now has an actual fix rather than a workaround.
You are not forced to update. Facepunch stated before release that this update is backwards compatible with existing servers, so players can still join servers that have not updated. Updating is still recommended, and the reasons are below.
The change that matters most: 64-bit
The update ships 64-bit binaries for the Windows game client, Windows dedicated servers, and most developer tools including Hammer. In Facepunch's own words, this means "there's now less risk of running out of the 32-bit memory address space and subsequently crashing when playing on heavy servers or with a lot of addons installed".
That sentence is the answer to a whole family of reports. A 32-bit process cannot address more than roughly 4 GB no matter how much memory the machine has, so a big Workshop collection or a large map would exhaust the address space and the engine would die. The classic form is:
Engine Error
CMDLCache:: Out of memoryPeople chased that with more RAM, which never helped, because the machine was never short of memory. The process was short of address space. A 64-bit build removes the ceiling.
On the Windows client the 64-bit build is selected from the Steam launch options rather than being forced on you. On Linux, 64-bit binaries have been available for some time on a separate branch, which is the subject of the branch section below.
Dedicated-server changes worth knowing
| Change | Why you care |
|---|---|
srcds_console.exe now ships (Windows only) | A variant of srcds.exe that does not open a new console window. Useful when a wrapper or panel already owns the console. |
New sv_log_storetime convar, default 0 | A number of hours to keep log files. With it set, old logs are dropped automatically instead of quietly filling the disk on a long-lived server. |
sv_logdownloadlist now defaults to 0 | Stops the server generating files in garrysmod/DownloadLists/ that nothing reads. If you have been wondering what that folder was, this is it. |
cache/workshop/ is cleaned up | Dedicated servers now remove cached Workshop content for addons that are no longer installed. Long-running servers accumulated this for years. |
sv_pure no longer defaults to mode 0 | Servers also stop trying to read files that are not shipped on every startup, which removes a recurring source of startup noise. |
| A new mountable game: Insurgency (2014, standalone) | One more source of maps and models that a map author can depend on. Worth knowing before a map on your server starts asking for it. |
There is also a new "Downloaded" category in the Addons menu, spawnmenu content tabs gained sub categories, and the player model selector was rebuilt with categories and better rendering. Those are client-side but they change what your players see when they arrive.
The branch situation, and why it is worth checking
Garry's Mod publishes several Steam branches for the dedicated server, and they do not all move together. Checked on 17 September 2026 for app 4020:
| Branch | What it is | Last build |
|---|---|---|
public | The default branch. This is where the September 2026 update landed. | 16 September 2026 |
x86-64 | 64-bit binaries. The branch Linux server owners have used to get a 64-bit runtime. | 15 September 2026 |
prerelease | Preview of the next default public version. | 16 September 2026 |
dev | Development branch, live daily updates. Not for production. | Daily |
network_test | Testing of network compatibility breaking changes. | 16 September 2026 |
The point to take away: if your server is pinned to x86-64, it did not receive the 16 September build, because that branch was last built the day before and has not moved since. That is not automatically a problem, since the update is backwards compatible and players can still join. It does mean you should check which branch you are on before assuming you have the new dedicated-server fixes.
Read the branch list yourself rather than trusting any guide, including this one. Steam publishes it:
steamcmd +login anonymous +app_info_update 1 +app_info_print 4020 +quitThe branches appear under a branches block, each with its own buildid and timestamp. Two branches showing different build ids means they are genuinely different builds, not a display quirk.
Should you update?
- Running a large Workshop collection on Windows: yes. The 64-bit dedicated server is the whole reason this update exists for you.
- Running a small sandbox server for friends: no urgency. Nothing forces it and nothing breaks if you wait.
- Running a heavily scripted gamemode: update a copy first. Backwards compatible is a statement about the network protocol, not a promise that every addon behaves identically.
- Chasing an out-of-memory crash: yes, and check whether you were on a 32-bit build all along.
Whatever you decide, take a backup of garrysmod/ before the update rather than after. Addons, configs and any gamemode data live there.
The full change list is published by the developers with each release: the September 2026 update notes.
Related Garry's Mod guides
- Server hardware requirements
- Dedicated-server setup
- Startup flags and server.cfg
- Missing textures and ERROR models
- Workshop addon safety
- Connection troubleshooting
Do not want to manage branch pins and update windows? Managed Garry's Mod hosting keeps the build current and backs up your addons before it moves.