Highly Performant & Scalable Ultima Online Server Emulator
https://www.modernuo.com
c-sharpcsharpcsharp-coredotnetdotnet-coreemulatorgplgplv3mmommo-enginemmorpgmmorpg-serveronlinerpgrunuoserverservuoultimaultima-onlineuo
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The ICU entry was inherited from the original package-name check (libicu-dev
on apt, libicu on dnf) and translated to a library probe without verifying
which library that should be. Three things were wrong with it.
libicui18n was never checked. The strings in libSystem.Globalization.Native.so
are exactly libicuuc and libicui18n, so probe both; libicudata arrives as a
dependency of libicuuc and the remaining ICU libraries are never referenced.
The probe accepted any SONAME down to .so.0, but the runtime's floor is
MinICUVersion 60. A host carrying only an older ICU passed the check and then
FailFast'd at startup. RHEL/CentOS 7 ships ICU 50 and is affected.
The ldconfig fast path bypassed the version range entirely, since a cache line
for libicuuc.so.50 still matches the "libicuuc.so" prefix, and it trusted a
stale cache: removing a library without refreshing the cache reported it
present. Drop it and ask the loader directly. dlopen consults the same cache
but answers the question we are actually asking, so this also removes the musl
special-case, where ldconfig exits 0 while producing nothing usable.
Add tzdata. It is data rather than a library, so no loader probe finds it, but
the event scheduler resolves configured zone IDs through TimeZoneInfo and
without /usr/share/zoneinfo every lookup except UTC throws. Slim containers
routinely omit it.
Move the rationale to dev-docs/platform-prerequisites.md so it is discoverable
without reading the build tool, covering what each dependency is for, why
InvariantGlobalization stays false, and the tzdata-legacy split on Debian 12
and Ubuntu 24.04 that hides aliases such as US/Eastern.
README no longer asks for libicu-dev. Matching the runtime package by pattern
('^libicu[0-9]+$') is version-independent without pulling in headers, so no
-dev package is required on any supported distribution.
Verified on Debian and Alpine: all present, each dependency removed
individually, a stale ldconfig cache, and ICU downgraded to .so.50.
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|---|---|---|
| .config | ||
| .github | ||
| branding | ||
| dev-docs | ||
| Distribution/Data | ||
| Projects | ||
| tools | ||
| .cursorrules | ||
| .editorconfig | ||
| .gitattributes | ||
| .gitignore | ||
| AGENTS.md | ||
| azure-pipelines.yml | ||
| CLAUDE.md | ||
| CODE_OF_CONDUCT.md | ||
| CONTRIBUTING.md | ||
| Directory.Build.props | ||
| FAQ.md | ||
| GEMINI.md | ||
| global.json | ||
| LICENSE | ||
| ModernUO.slnx | ||
| publish.cmd | ||
| publish.ps1 | ||
| publish.sh | ||
| README.md | ||
| rider-settings.zip | ||
| Rules.ruleset | ||
| SPONSORS.md | ||
| stylecop.json | ||
| THIRD-PARTY-NOTICES | ||
| version.json | ||
ModernUO 
Ultima Online Server Emulator for the modern era!
Requirements
Supported Operating Systems
Required Frameworks
All Operating Systems
Windows
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