This document contains a list of all warnings and errors that may occur during restore.

Errors

Non-specific errors and warnings

NU1000

Issue

Generic error from NuGet.

NU1500

Issue

Generic warning from NuGet.

Invalid inputs

NU1001

Issue

The project does not contain one or more frameworks.

Common causes

The project does not contain a TargetFramework or TargetFrameworks property.

Example

The project projA does not specify any target frameworks in c:\tmp\projA.csproj.

NU1002

Issue

Invalid combination of inputs along with a CLEAR keyword.

Common causes

CLEAR may not be combined with other inputs.

Example

'CLEAR' cannot be used in conjunction with other values.

NU1003

Issue

PackageTargetFallback and AssetTargetFallback provide different behavior for selecting assets and can not be used together.

Common causes

Both PackageTargetFallback and AssetTargetFallback exist in the project.

Example

PackageTargetFallback and AssetTargetFallback cannot be used together. Remove PackageTargetFallback(deprecated) references from the project environment.

Missing packages and projects

NU1100

Issue

A dependency group not be resolved. This is a generic issue for types that are not packages or projects.

Common causes

The project contains a dependency on an item that does not exist.

Example

Unable to resolve System.Missing for net45

NU1101

Issue

The package id cannot be found on any sources.

Common causes

The correct package source is missing or the package id has a typo.

Example

Unable to find package System.Missing. No packages exist with this id in source(s): dotnet-core, dotnet-roslyn, NuGet.org

NU1102

Issue

The package id is found but a version within the specified dependency range cannot be found on any of the sources.

Common causes

The correct package source is missing or the dependency range is incorrect. The range might be specified by a package and not the user.

The user may need to switch to an available version if this package is referenced by the project directly.

Example

Unable to find package NuGet.Versioning with version (>= 9.0.1)
  - Found 30 version(s) in NuGet.org [ Nearest version: 4.0.0 ]
  - Found 10 version(s) in dotnet-buildtools [ Nearest version: 4.0.0-rc-2129 ]
  - Found 9 version(s) in NuGetVolatile [ Nearest version: 3.0.0-beta-00032 ]
  - Found 0 version(s) in dotnet-core
  - Found 0 version(s) in dotnet-roslyn

NU1103

Issue

No stable versions were found in the dependency range. Pre-release versions were found but are not allowed.

Common causes

The project specified a stable version for the dependency range. Users need to change this to include pre-release versions.

Example

Unable to find a stable package NuGet.Versioning with version (>= 3.0.0)
  - Found 10 version(s) in dotnet-buildtools [ Nearest version: 4.0.0-rc-2129 ]
  - Found 9 version(s) in NuGetVolatile [ Nearest version: 3.0.0-beta-00032 ]
  - Found 0 version(s) in dotnet-core
  - Found 0 version(s) in dotnet-roslyn

NU1104

Issue

A ProjectReference points to a file that does not exist.

Common causes

The project file is missing from disk or the reference is incorrect.

Example

Project reference does not exist 'c:\a.csproj'. Check that the project reference is valid and that the project file exists.

NU1105

Issue

The project file exists but no restore information was provided for it.

Common causes

In Visual Studio this could mean that the project is unloaded. From the command line this could mean that the file is corrupt or that it does not contain the custom after imports target needed for restore to read the project.

Example

Unable to read project information for 'c:\a.csproj'. The project file may be invalid or missing targets required for restore.

NU1106

Issue

Dependency constraints cannot be resolved.

Common causes

Packages contain dependency on exact versions of a package instead of open ended ranges.

Example

Unable to satisfy conflicting requests for {id}: {conflict path} Framework: {target graph}

NU1107 (Previously NU1607)

Issue

Unable to resolve dependency constraints between packages.

Common causes

Packages with dependency constraints on exact versions do not allow other packages to increase the version if needed.

Example

Version conflict detected for NuGet.Versioning. Reference the package directly from the project to resolve this issue.
  NuGet.Packaging 3.5.0 -> NuGet.Versioning (= 3.5.0)
  NuGet.Configuration 4.0.0 -> NuGet.Versioning (= 4.0.0)

NU1108 (Previously NU1606)

Issue

A circular dependency was detected.

Common causes

A package is authored incorrectly.

Example

Cycle detected: A -> B -> A

Compatibility

NU1201

Issue

A dependency project does not contain a framework compatible with the current project.

Common causes

The project's target framework is a higher version than the consuming project.

Example

Project ServerWeb is not compatible with netstandard1.3 (.NETStandard,Version=v1.3). Project ServerWeb supports:
  - netstandard1.6 (.NETStandard,Version=v1.6)
  - netcoreapp1.0 (.NETCoreApp,Version=v1.0)

NU1202

Issue

A dependency package does not contain any assets compatible with the project.

Common causes

The package does not support the project's target framework.

Example

Package System.ComponentModel.EventBasedAsync 4.0.11 is not compatible with netstandard1.3 (.NETStandard,Version=v1.3). Package System.ComponentModel.EventBasedAsync 4.0.11 supports:
  - monoandroid10 (MonoAndroid,Version=v1.0)
  - monotouch10 (MonoTouch,Version=v1.0)
  - net45 (.NETFramework,Version=v4.5)
  - netcore50 (.NETCore,Version=v5.0)
  - netstandard1.0 (.NETStandard,Version=v1.0)
  - portable-net45+win8+wp8+wpa81 (.NETPortable,Version=v0.0,Profile=Profile259)
  - win8 (Windows,Version=v8.0)
  - wp8 (WindowsPhone,Version=v8.0)
  - wpa81 (WindowsPhoneApp,Version=v8.1)
  - xamarinios10 (Xamarin.iOS,Version=v1.0)
  - xamarinmac20 (Xamarin.Mac,Version=v2.0)
  - xamarintvos10 (Xamarin.TVOS,Version=v1.0)
  - xamarinwatchos10 (Xamarin.WatchOS,Version=v1.0)

NU1203

Issue

The package does not support the project's RuntimeIdentifier.

Common causes

The package does not support the current RuntimeIdentifier. Change the RuntimeIdentifiers used in the project if needed.

Example

System.Example 1.0.0 provides a compile-time reference assembly for a.dll on net461, but there is no compatible run-time assembly.

NU1401

Issue

The package requires features or frameworks not currently supported by the installed version of NuGet.

Common causes

Upgrade NuGet to fix the issue.

Example

The 'NuGet.Versioning' package requires NuGet client version '5.0.0' or above, but the current NuGet version is '4.3.0'. To upgrade NuGet, please go to http://docs.nuget.org/consume/installing-nuget.

Warnings

Invalid inputs

NU1501

Issue

The project restore is attempting to operate on was not found.

Common causes

The project is missing.

Example

The folder 'c:\projects\a' does not contain a project to restore.

NU1502

Issue

RuntimeSupports contains an invalid profile.

Common causes

The supports profile was not found in a runtime.json file from the current dependency packages.

Example

Unknown Compatibility Profile: aaa

NU1503

Issue

A dependency project does not import NuGet's restore targets. This is similar to NU1105 but here the project is skipped and ignored instead of causing all of restore to fail. In complex solutions there are often other types of projects that may not support restore.

Common causes

This can happen for projects that do not import common props/targets which automatically import restore. If the project does not need to be restored this can be ignored.

Example

Skipping restore for project 'c:\a.csproj'. The project file may be invalid or missing targets required for restore. 

Unexpected package versions

NU1601

Issue

A direct project dependency was bumped to a higher version than the project specified.

Common causes

Another dependency package required a higher version and bumped the package up.

Example

Dependency specified was NuGet.Versioning (>= 3.5.0) but ended up with NuGet.Versioning 4.0.0.

NU1602

Issue

A package dependency is missing a lower bound. This does not allow restore to find the best match. Each restore will float downwards trying to find a lower version that can be used. This means that restore goes online to check all sources each time instead of using the packages that already exist in the user package folder.

Common causes

This is usually a package authoring error.

Example

NuGet.Packaging 4.0.0 does not provide an inclusive lower bound for dependency NuGet.Versioning (> 3.5.0). An approximate best match of 3.6.0 was resolved.

NU1603

Issue

A package dependency specified a version that could not be found. A higher version was used instead, which differs from what the package was authored against.

This means that restore did not find the best match. Each restore will float downwards trying to find a lower version that can be used. This means that restore goes online to check all sources each time instead of using the packages that already exist in the user package folder.

Common causes

The package sources do not contain the expected lower bound version. If the package expected has not been released then this may be a package authoring error.

Example

NuGet.Packaging 4.0.0 depends on NuGet.Versioning (>= 4.0.0) but 4.0.0 was not found. An approximate best match of 5.0.0 was resolved.

NU1604

Issue

A project dependency does not define a lower bound.

This means that restore did not find the best match. Each restore will float downwards trying to find a lower version that can be used. This means that restore goes online to check all sources each time instead of using the packages that already exist in the user package folder.

Common causes

The project's PackageReference Version attribute should be updated to include a lower bound.

Example

Project dependency NuGet.Versioning (<= 9.0.0) does not contain an inclusive lower bound. Include a lower bound in the dependency version to ensure consistent restore results.

NU1605

Issue

A dependency package specified a version constraint on a higher version of a package than restore ultimately resolved.

Common causes

Nearest wins when resolving packages. A nearer package in the graph may have overridden a distant package.

Example

Detected package downgrade: NuGet.Versioning from 4.0.0 to 3.5.0. Reference the package directly from the project to select a different version.
  NuGet.Packaging 3.5.0 -> NuGet.Versioning 3.5.0
  NuGet.Commands 4.0.0 -> NuGet.Configuration 4.0.0 -> NuGet.Versioning 4.0.0

Resolver conflicts

NU1608

Issue

A resolve package is higher than a dependency constraint allows. In some cases this is intentional and the warning can be suppressed.

Common causes

A package referenced directly by a project will override dependency constraints from other packages.

Example

Detected package version outside of dependency constraint: x 1.0.0 requires y (= 1.0.0) but version y 2.0.0 was resolved.

Package fallback

NU1701

Issue

PackageTargetFallback was used to select assets from a package. This is a warning to let the user know that the assets may not be 100% compatible.

Common causes

The package does not support the project framework.

Example

Package 'NuGet.Versioning' was restored using 'portable-net45+win8' instead the project target framework 'netstandard1.5'. This package may not be fully compatible with your project.

Feed warnings

NU1801

Issue

An error occurred when reading the feed. IgnoreFailedSources was set to true, converting it to a non-fatal warning. This could contain any message and is generic.

Common causes

The source is invalid.