NuGet NU1101 "Unable to find package" in CI

By Kaveh Alemi·Latchkey

NU1101 is the resolver code for "no configured source has this package id at all". It is emitted when the id itself cannot be located, before any version constraint is even considered.

What this error means

restore fails with "error NU1101: Unable to find package X. No packages exist with this id in source(s): ..." naming the sources it searched.

dotnet

error NU1101: Unable to find package Serilog.Sinks.Custom. No packages exist with this id
      in source(s): nuget.org, private

Common causes

The private feed is not configured in CI

The package is internal, but the runner only has nuget.org, so NuGet finds no source that lists the id.

A typo or renamed package id

The id in the PackageReference does not match any published id on the searched sources.

How to fix it

Add the missing source

Configure the private feed the package lives on so NU1101 resolves to a real source.

Terminal

dotnet nuget add source https://pkgs.internal.example.com/nuget/v3/index.json --name private

Fix the package id

Read the id NuGet could not find in the NU1101 line.
Compare it against the published id on the feed.
Correct the Include and restore again.

How to prevent it

Commit nuget.config with all required feeds so CI matches local.
Validate package ids at review time.
Keep private feed sources in sync across repositories.

Frequently asked questions

What causes "NU1101"?