Highly Performant & Scalable Ultima Online Server Emulator
https://www.modernuo.com
c-sharpcsharpcsharp-coredotnetdotnet-coreemulatorgplgplv3mmommo-enginemmorpgmmorpg-serveronlinerpgrunuoserverservuoultimaultima-onlineuo
114dbba6e2
## The bug Pet is set to follow. It gets attacked and defends itself (the order flips to `Attack`), or the player tells it to `come`. The player then says `stop`. The pet quietly stops following and starts idle-wandering — the player has to re-issue the order to get it back. `ResolveStop` clears `ControlTarget`, since the transient order that is ending owns it, and then resumes the standing order. Nothing restores a target, so the resumed `Follow` has none. `DoOrderFollow` checks for a target before anything else, finds none on the very next think, says "I have no one to follow" and cancels the order to `None`: ``` follow standing order=Follow target=set persist=Follow cur=0.2 => move=0.3 attacked (defends) order=Attack target=set persist=Follow cur=0.2 => move=0.3 stop issued order=Follow target=null persist=Follow cur=0.2 => move=0.3 next think order=None target=null persist=Follow cur=0.4 => move=0.9 ``` Two things go wrong at once: - `PersistentOrder` still reads `Follow` while `ControlOrder` is `None`, so the pet never recovers on its own. - The pace falls from the active clock to the passive one. A shard that tunes `SetMoveSpeed(active, passive)` sees a following pet drop from its active move speed to its passive one for no visible reason — which is how this surfaced. Era-independent. Guard is unaffected: `DoOrderGuard` works off `ControlMaster`, not `ControlTarget`. ## The fix A standing `Follow` does not always mean "follow the master" — a pet friend can point it elsewhere with `all follow me` / `*follow me` (0x163, 0x16C) or `*follow` plus a target pick. So `SetPersistentOrder` remembers the target the standing order was given, and `ResumePersistentOrder` restores it, falling back to the master only when that target is gone. The field is runtime-only, like `PersistentOrder` itself. Doing this in `ResumePersistentOrder` rather than `ResolveStop` also covers the Friend/Unfriend/Transfer resumes, where `ControlTarget` points at a third party and the pet would otherwise have resumed its follow on *them*. It matches what `HandleInvalidControlTarget` already does before its own resume. ## Tests `Stop_WhileAttacking_FallsBackToPersistentFollow` already existed and passed, because it asserted the resumed order without checking for a target or driving a think tick. Three tests added alongside it: - `Stop_WhileAttacking_ResumedFollowTargetsTheMaster` - `Stop_WhileAttacking_ResumedFollowKeepsAPetFriendAsItsTarget` — a friend's follow order is not hijacked back to the owner - `Stop_WhileAttacking_ResumedFollowSurvivesTheNextThink` — the one that catches the cancellation Each was confirmed to fail without the change (`Expected: Follow, Actual: None`; wrong target). Full suites green: 782 UOContent, 869 Server. |
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| global.json | ||
| LICENSE | ||
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| publish.sh | ||
| README.md | ||
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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