ASP.NET - 在 VS 2017 中浏览 Nuget 包时出现“根级别的数据无效”错误

Question

I'm trying to create a .NET Web API Application and install EntityFramework using Nuget Package Manager.

But when I'm going to : Right Click on Project References > Manage Nuget Packages > Browse I can't find Microsoft.EntityFrameworkCore in the list.

Then I'm having this error showing at the bottom, in the output section :

[nuget.org] Data at the root level is invalid. Line 1, position 1.

I use VS 2017 15.5.2 and .Net Framework 4.7.02556 .

I also get this error when using the dotnet cli command dotnet add package Microsoft.EntityFrameworkCore :

error: The content at 'https://api.nuget.org/v3/index.json/FindPackagesById()?id='Microsoft.EntityFrameworkCore'' is not valid XML. error: Data at the root level is invalid. Line 1, position 1.

It looks like that the dotnet cli is trying to load the remote index.json file as a XML file.

For your information, dotnet --version is showing 2.1.3 .

Any idea?

Answer 1

ASP.NET - “Data at the root level is invalid” error while browsing Nuget Packages in VS 2017

According to the error log,

Data at the root level is invalid. Line 1, position 1.

It looks like an error with XML formatting in your project, such as, web.config or NuGet.Config (Path:%appdata%\\NuGet). So please check your xml file for any anomalies, remove everything before <?xml version="1.0" encoding="utf-8"?> .

If you still could not find any anomalies in your project, please create a new blank project without any modification, then Right Click on Project References > Manage Nuget Packages > Browse, to find the package Microsoft.EntityFrameworkCore .

As test, I created aa .NET Web API Application project, changed the first line in the web.config file from:

`<?xml version="1.0" encoding="utf-8"?>`

To:

zzxml version="1.0" encoding="utf-8"?>

Then open Package Manager Console, install some package with command line, I will get that error:

Answer 2

Using VS 2019, my solution was to Clear All NuGet Cache(s) .

This can be achieved through Options -> NuGet Package Manager -> General -> Clear All NuGet Cache(s).

Answer 3

It looks like the error came from the %appdata%/Roaming/NuGet/NuGet.Config file There was no syntax error in this file but I just deleted it and reopened VS 2017 that created another NuGet.Config with less data than the deleted one. Then the error disappeared.

Answer 4

我刚刚删除了文件 c:\\Users{username}\\AppData\\Roaming\\NuGet\\NuGet.Config 并且 Visual Studio 2015 再次与 nuget.org 一起工作。

Answer 5

I had a trailing semicolon on my package source. Removing that, and then restarting Visual Studio fixed the problem. I had a custom NuGet.Config file defined in the same folder as my *.sln , but this also would cause issues on your %appdata%/NuGet/NuGet.Config path too.

Answer 6

I've seen this happen before when hidden characters get into the file.. Editing this file with bitbucket online editor, you can see the red dots? These indicate some un-printable characters, that will cause the same error stated above, a corrupted nuget.config

Answer 7

In My Case I have follow the below steps :

1. Repair the Visual studio 2019 using Visual studio installer app.

2. Clear all nugate cashes using Tools ==> Option ==> Nugate Package Manager ==> General ==> Clear All NuGage Cache(s).

3. Clean Solution and Build the solution.

Answer 8

Following helped me resolving this issue.

1. Clear all nugate cashes using Visual Studio Tools ==> Option ==> Nuget Package Manager ==> General ==> Clear All NuGet Cache(s).
2. Close Visual Studio.
3. Went to my project in VS Command Prompt where the .sln file is located (ie C:\\Projects\\Project1)
4. Executed below command to restore all nuget packages: msbuild -t:restore
5. Open the project in Visual Studio and rebuild SOLUTION from VS.