Highly Performant & Scalable Ultima Online Server Emulator
https://www.modernuo.com
c-sharpcsharpcsharp-coredotnetdotnet-coreemulatorgplgplv3mmommo-enginemmorpgmmorpg-serveronlinerpgrunuoserverservuoultimaultima-onlineuo
ab738d90af
Pet and summon bugs found by the master-reference audit for #2592 (comments there have the full inventory). Independent of delta saves. ## Releasing a pet never finished The Release order ran two half-releases that never met: - The order handler cleared the master. That set `Controlled` to false, so `Obey` never ran again and the think-side `DoOrderRelease` (re-home, three-day delete timer, backpack drop) was dead code: a released pet kept its pack and never despawned. - The loyalty drain called `DoOrderRelease` directly, so a pet whose loyalty hit zero got the countdown and dropped its pack but kept its master and its owner's follower slots, the opposite of the code comment's intent. `DoOrderRelease` is now the whole release (targets, bonding, `SetControlMaster(null)`, re-home, delete or countdown, pack drop) and runs once, synchronously, from the handler or the loyalty drain. Summons still die on release, as before. Two tests pin both entry points: master cleared, follower slots returned, countdown running, home anchored. This is the one place the `PetOrders` / `PetOrderHandlers` split bit; the wider audit of that duplication is a separate task. ## Summon master follows the pet Transfer, stable claim, GM "obey" and Ball of Summoning copied `SummonMaster` only when `Summoned`, so a talisman summon (`Summoned` is false, `SummonMaster` set) kept its original summoner after a transfer: two different masters on one creature, with the original summoner's area spells still exempting it. They now mirror the summon master whenever it is set. Jail stabling cleared only `ControlMaster`, so a jailed talisman summon kept charging the summoner's follower slots; it now clears both, like the stable master and auto-stable already do. ## Small ones - The faction horse breeder set `Controlled`/`ControlMaster` directly; it now goes through `SetControlMaster` and tells the buyer why it refused (1049607) instead of silently deleting the horse. - `Notoriety` dereferenced `SummonMaster` on a summoned creature without a null check. ## Tests UOContent.Tests 778 green (two new). |
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ModernUO 
Ultima Online Server Emulator for the modern era!
Requirements
Supported Operating Systems
Required Frameworks
All Operating Systems
Windows
Hardware
| Use | vCPU | RAM | Storage |
|---|---|---|---|
| Development / test | 2 dedicated | 2 GB | SSD |
| Small live shard (< 50 concurrent) | 4 dedicated | 4 GB | NVMe |
| Medium (50–200) | 4–8 | 8 GB | NVMe |
| Large (200+) | 8+, high clock | 16 GB+ | NVMe |
See dev-docs/server-requirements.md for more information.
Development
Supported IDEs
Getting Started
- Install prerequisite requirements
- Clone this repository (or download the latest):
git clone https://github.com/modernuo/ModernUO.git
- Open
ModernUO.slnto start developing
Building/Publishing
Interactive Mode (Recommended for new users)
Run ./publish.cmd (Windows) or ./publish.sh (Linux/macOS) with no arguments to launch the guided build tool. It will:
- Check prerequisites (.NET SDK, native libraries)
- Walk you through configuration and platform selection
- Build and publish the server to the
Distributiondirectory - Show deployment instructions for cross-compiled builds
Command Line
./publish.cmd [release|debug] [os] [arch]
os- Supported operating systemsarchx64- Intel/AMD 64-bitarm64- ARM 64-bit
Linux Prerequisites
Fedora, CentOS, RHEL, AlmaLinux, Rocky, etc
dnf upgrade --refresh -y
# RHEL-family distributions (CentOS Stream, AlmaLinux, Rocky, RHEL) need CRB and EPEL enabled.
# Fedora skips this block.
dnf install -y dnf-plugins-core
dnf config-manager --set-enabled crb
dnf install -y epel-release
# Prerequisites
dnf install -y findutils libicu libdeflate libargon2 tzdata
Ubuntu, Debian, etc
apt-get update -y
# The ICU runtime package carries the ABI version in its name (libicu74, libicu76, …) and has no
# stable alias, so match it by pattern rather than pinning a release-specific name.
apt-get install -y '^libicu[0-9]+$' libdeflate0 libargon2-1 tzdata
Only the runtime libraries are needed — the -dev/-devel packages are not. Run
./build-tool --check-prereqs to check the current machine and print the exact packages your
release needs.
zstd is not listed because ZstdNet bundles libzstd for every platform, and liburing is not
listed because IORingGroup issues io_uring syscalls directly.
If the shard's configured time zone is a legacy alias such as US/Eastern, Debian 12 and Ubuntu
24.04 also need tzdata-legacy. See Platform Prerequisites
for what each dependency is for and what breaks without it.
OSX Requirements
brew install icu4c libdeflate argon2
Running the Server
- Follow the publish instructions
- The
Distributiondirectory is portable — copy it to your production server for deployment - Run
ModernUO.exeordotnet ModernUO.dllfrom theDistributiondirectory - On first run, the server will prompt you to configure game data file locations
Troubleshooting / FAQ
- See FAQ
Want to sponsor?
Thank you for supporting us! You can find out how by visiting the sponsors page.
Collaborators
Thanks
- RunUO Team & Community
- Voxpire, the ServUO Team & Community
- Karasho, Jaedan and the ClassicUO Community
Development Tools & Plugins provided with ♥ by
Code Signing Policy
Free code signing provided by SignPath.io, certificate by SignPath Foundation.
This program will not transfer any information to other networked systems unless specifically requested by the user or the person installing or operating it
Teams & Roles
Approvers & Committers: Development Team