Error nu1301: unable to load the service index for source

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NuGet Error NU1301

• Article
• 05/16/2022
• 2 minutes to read

In this article

The local source 'C:\Code\Contoso\contosoLocalSource' doesn't exist.

Issue

Restore could not be completed because the listed source is unavailable.

Solution

Consult the error message for more details. You may need to inform the source owner as there might be issues that only they can address.

Alternatively, you can try removing the source from the configuration retry again. The configured source may not be necessary for your build.

Visual Studio 2022 gives an error when trying to browse NuGet.

I get these errors on 2 different Windows Servers (2016) I’ve tried. One running Visual Studio 2017, the other running Visual Studio 2019 and 2022.

Visual Studio 2017:

“[nuget.org] Unable to load the service index for source https://api.nuget.org/v3/index.ison.
An error occurred while sending the request.
The underlying connection was closed: An unexpected error occurred on a send.
Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.
An existing connection was forcibly closed by the remote host.”

Visual Studio 2022:

[nuget.org] Unable to load the service index for source https://api.nuget.org/v3/index.json. An error occurred while sending the request. The underlying connection was closed: An unexpected error occurred on a send. Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host. An existing connection was forcibly closed by the remote host

Note that we do not use a proxy.

Loading https://api.nuget.org/v3/index.json with both Chrome and Edge work.
Loading https://api.nuget.org/v3/index.json with Internet Explorer returns:

“This page can’t be displayed
Turn on TLS 1.0, TLS 1.1, and TLS 1.2 in Advanced settings and try connecting to https://api.nuget.org again. If this error persists, it is possible that this site uses an unsupported protocol or cipher suite such as RC4 (link for the details), which is not considered secure. Please contact your site administrator.”

Things I’ve tried that have failed to resolve it

updated Visual Studio

Clearing nuget cache from within Visual Studio

Deleted NuGet.Config from C:\Users\<user>\AppData\Roaming\NuGet

Modified C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\Common7\IDE\devenv.com based on tips I found. I know it’s possible that what I changed was not correct. Reverted back.

Registry changes:

Computer\HKEY LOCAL MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.0\Client
Computer\HKEY LOCAL MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.1\Client
Computer\HKEY LOCAL MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.3\Client

 DisabledByDefault = 1
 Enabled = 0

Computer\HKEY LOCAL MACHINE\SYSTEM\ CurrentControl Set) Control SecurityProviders \SCHANNEL\Protocols\TLS 1.2\Client

 DisabledByDefault = 0
 Enabled = 1

Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft.NETFramework\v2.0.50727
Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft.NETFramework\v4.0.30319
Computer\HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft.NETFramework\v2.0.50727
Computer\HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft.NETFramework\v4.0.30319

 SchUseStrongCrypto = 1
 SystemDefaultTlsVersions = 1

Tried moving the server's Active Directory object out of the current AD OU which has a Group Policy configured with specific ciphers enabled, and the order of preference, into a new OU with this NOT configured.

Tried disabling anti-virus software

Reference links, things I've tried or looked into:
https://docs.microsoft.com/en-us/security/engineering/solving-tls1-problem
https://docs.microsoft.com/en-us/troubleshoot/azure/active-directory/enable-support-tls-environment?tabs=azure-monitor%22%20%5Cl%20%22registry-strings
https://stackoverflow.com/questions/41185443/nuget-connection-attempt-failed-unable-to-load-the-service-index-for-source

At this point, I'm run out of ideas. It seems like Visual Studio is not adhering to the system's default TLS settings (1.2) but it could possibly be something else.

Is API NuGet org down?

Where is the NuGet config file located?

How do I check NuGet version?

How do I run a dotnet restore in Visual Studio 2019?