.NET SDK Version Mismatch Fix

In this tutorial, you'll learn about .net sdk version mismatch fix. We cover key concepts, practical examples, and best practices.

The Problem

Building fails with:

NETSDK1045: The current .NET SDK does not support targeting .NET 9.0. Either target .NET 8.0 or lower, or use a version of the .NET SDK that supports .NET 9.0.

The installed SDK version does not support the target framework specified in your project.

Quick Fix

Step 1: Check SDK and framework versions

WRONG -- assuming the latest SDK supports all frameworks:

dotnet --version

RIGHT -- list all installed SDKs:

dotnet --list-sdks

Compare with your project's TargetFramework.

Step 2: Update or create global.json

WRONG -- no global.json, build behavior changes across machines:

dotnet new globaljson --sdk-version 9.0.100

RIGHT -- pin SDK version and allow roll-forward:

{
  "sdk": {
    "version": "8.0.400",
    "rollForward": "latestFeature"
  }
}

Options for rollForward:

• patch -- exact patch version
• feature -- same major.minor, any feature band
• latestFeature -- latest feature band within major.minor
• latestMajor -- any higher version

Step 3: Install or upgrade the SDK

WRONG -- installing only the runtime for build:

sudo apt install dotnet-runtime-8.0  # cannot build

RIGHT -- install the full SDK:

sudo apt install dotnet-sdk-8.0

Or use the install script:

curl -sSL https://dot.net/v1/dotnet-install.sh | bash /dev/stdin --channel 8.0

Step 4: Change target framework

WRONG -- targeting a preview framework without the matching SDK:

<TargetFramework>net10.0</TargetFramework>

RIGHT -- target the latest released framework:

<TargetFramework>net9.0</TargetFramework>

Step 5: Check CI/CD SDK version

WRONG -- CI uses a different SDK than local:

# GitHub Actions
- name: Setup .NET
  uses: actions/setup-dotnet@v4
  # no version specified -- uses default

RIGHT -- pin the SDK version in CI:

- name: Setup .NET
  uses: actions/setup-dotnet@v4
  with:
    dotnet-version: '8.0.x'

Prevention

• Commit a global.json to the repository root with the required SDK version.
• Use the same SDK version in local development and CI/CD.
• Run dotnet --list-sdks before troubleshooting build failures.
• Use rollForward: latestFeature in global.json to allow minor SDK updates.
• Update global.json when upgrading the SDK across your team.

Common Mistakes with sdk version

1. Forgetting that lazy evaluation defers computation until the value is forced, causing space leaks with unevaluated thunks
2. Using return to exit a function early instead of wrapping a pure value in the monad
3. Mixing let bindings with <- bindings in do notation, producing type errors

These mistakes appear frequently in real-world DOTNET code. DodaTech's contributors have identified these patterns through analysis of open-source projects and production systems.

Practice Exercise

Write a pure function that safely divides two integers using Maybe, then test it with edge cases like division by zero and negative numbers.

This exercise reinforces the concepts covered in this guide. Try implementing it before checking online solutions.

FAQ