.NET MAUI Doctor

Validate and fix .NET MAUI development environments. All version requirements are discovered dynamically from NuGet APIs — never hardcode versions.

When to Use

Setting up a new .NET MAUI development environment
Build errors mentioning missing SDKs, workloads, JDK, or Android components
Errors like "Android SDK not found", "Java version", or "Xcode not found"
Verifying environment health after SDK or OS updates

When Not to Use

Non-MAUI .NET projects (use standard .NET SDK troubleshooting instead)
Xamarin.Forms apps (different toolchain and workload requirements)
Runtime app crashes unrelated to environment setup
App store publishing or signing issues
IDE-specific issues (Visual Studio or VS Code configuration)

Important: .NET Version Currency

Your training data may be outdated regarding .NET versions. .NET ships new major releases annually (November). Always check the releases-index.json (Task 2) to discover the latest active major release — do not assume your training data reflects the current version. For example, if you know about .NET 9.0 but the releases index shows .NET 10.0 as active, use .NET 10.0.

Inputs

A development machine running macOS, Windows, or Linux
Shell access (Bash on macOS/Linux, PowerShell on Windows)
Internet access for NuGet API queries and SDK downloads
Admin/sudo access may be required for installing SDKs and workloads
Bash prerequisites: curl, jq, and unzip (macOS/Linux)
PowerShell prerequisites: Invoke-RestMethod and System.IO.Compression (built-in on Windows)

Behavior

Run through ALL tasks autonomously
Re-validate after each fix
Iterate until complete or no further actions possible
After detecting platform (Task 1), load only the matching platform-specific references

Workflow

Task 1: Detect Environment

bash

# macOS
sw_vers && uname -m

# Windows
systeminfo | findstr /B /C:"OS Name" /C:"OS Version"

# Linux
cat /etc/os-release && uname -m

After detection, load the matching platform references:

macOS: references/platform-requirements-macos.md, references/installation-commands-macos.md, references/troubleshooting-macos.md
Windows: references/platform-requirements-windows.md, references/installation-commands-windows.md, references/troubleshooting-windows.md
Linux: references/platform-requirements-linux.md

Task 2: Check .NET SDK

bash

dotnet --info

Compare installed vs latest-sdk from https://dotnetcli.blob.core.windows.net/dotnet/release-metadata/releases-index.json where support-phase is "active".

Task 3: Check MAUI Workloads

Workload	macOS	Windows	Linux
`maui`	Required	Required	❌ Use `maui-android`
`maui-android`	Alias	Alias	Required
`android`	Required	Required	Required
`ios`	Required	Optional	N/A

Task 4: Discover Requirements from NuGet

See references/workload-dependencies-discovery.md for complete process.

Query NuGet for workload manifest → extract WorkloadDependencies.json → get:

jdk.version range and jdk.recommendedVersion
androidsdk.packages, buildToolsVersion, apiLevel
xcode.version range

Task 5: Validate Java JDK

Only Microsoft OpenJDK supported. Verify java -version output contains "Microsoft". See references/microsoft-openjdk.md for detection paths.

Use the JDK version recommended by WorkloadDependencies.json (jdk.recommendedVersion), ensuring it satisfies the jdk.version range. Do not hardcode JDK versions.

JAVA_HOME is NOT required. .NET MAUI tools auto-detect Microsoft OpenJDK installations from known paths. Do not tell users to set JAVA_HOME — it is unnecessary and risks pointing to a non-Microsoft JDK.

JAVA_HOME state	OK?	Action
Not set	✅	None needed — auto-detection works
Set to Microsoft JDK	✅	None needed
Set to non-Microsoft JDK	⚠️	Report as anomaly — let user decide to unset or redirect

Task 6: Validate Android SDK

Check packages from androidsdk.packages, buildToolsVersion, apiLevel (Task 4). See references/installation-commands.md for sdkmanager commands.

Task 7: Validate Xcode (macOS Only)

bash

xcodebuild -version

Compare against xcode.version range from Task 4. See references/installation-commands-macos.md.

Task 8: Validate Windows SDK (Windows Only)

The Windows SDK is typically installed as part of the .NET MAUI workload or Visual Studio. See references/installation-commands-windows.md.

Task 9: Remediation

See references/installation-commands.md for all commands.

Key rules:

Workloads: Always use --version flag. Never use workload update or workload repair.
JDK: Only install Microsoft OpenJDK. Do not set JAVA_HOME (auto-detected).
Android SDK: Use sdkmanager (from Android SDK command-line tools). On Windows use sdkmanager.bat.

Task 10: Re-validate

After each fix, re-run the relevant validation task. Iterate until all checks pass.

Validation

A successful run produces:

.NET SDK installed and matches an active release
All required workloads installed with consistent versions
Microsoft OpenJDK detected (java -version contains "Microsoft")
All required Android SDK packages installed (per WorkloadDependencies.json)
Xcode version in supported range (macOS only)
Windows SDK detected (Windows only)

Build Verification (Recommended)

After all checks pass, create and build a test project to confirm the environment actually works:

bash

TEMP_DIR=$(mktemp -d)
dotnet new maui -o "$TEMP_DIR/MauiTest"
dotnet build "$TEMP_DIR/MauiTest"
rm -rf "$TEMP_DIR"

On Windows, use $env:TEMP or New-TemporaryFile for the temp directory.

If the build succeeds, the environment is verified. If it fails, use the error output to diagnose remaining issues.

Run Verification (Optional — Ask User First)

After a successful build, ask the user if they want to launch the app on a target platform to verify end-to-end:

bash

# Replace net10.0 with the current major .NET version
dotnet build -t:Run -f net10.0-android
dotnet build -t:Run -f net10.0-ios        # macOS only
dotnet build -t:Run -f net10.0-maccatalyst # macOS only
dotnet build -t:Run -f net10.0-windows    # Windows only

Only run the target frameworks relevant to the user's platform and intent. This step deploys to an emulator/simulator/device, so confirm with the user before proceeding.

Common Pitfalls

maui vs maui-android workload: On Linux, the maui meta-workload is not available — use maui-android instead. On macOS/Windows, maui installs all platform workloads.
workload update / workload repair: Never use these commands. Always install workloads with an explicit --version flag to ensure version consistency.
Non-Microsoft JDK: Only Microsoft OpenJDK is supported. Other distributions (Oracle, Adoptium, Azul) will cause build failures even if the version is correct.
Unnecessary JAVA_HOME: Do not set JAVA_HOME. MAUI auto-detects JDK from known install paths. If JAVA_HOME is set to a non-Microsoft JDK (e.g., Temurin), report this as an anomaly — it may override auto-detection and cause failures. Let the user decide whether to unset it.
Hardcoded versions: Never hardcode SDK, workload, or dependency versions. Always discover them dynamically from the NuGet APIs (see Task 4).
Android SDK sdkmanager on Windows: Use sdkmanager.bat, not sdkmanager, on Windows.
Stale training data: LLM training data may reference outdated .NET versions. Always check the releases-index.json to discover the current active release.

References

references/workload-dependencies-discovery.md — NuGet API discovery process
references/microsoft-openjdk.md — JDK detection paths, identification, JAVA_HOME
references/installation-commands.md — .NET workloads, Android SDK (sdkmanager)
references/troubleshooting.md — Common errors and solutions
references/platform-requirements-{platform}.md — Platform-specific requirements
references/installation-commands-{platform}.md — Platform-specific install commands
references/troubleshooting-{platform}.md — Platform-specific troubleshooting

Official docs: