Permission denied to modify the 'C:\Program Files\dotnet\sdk\NuGetFallbackFolder' folder.

[Tadimsky]

Steps to reproduce

Run dotnet build or any dotnet command after installing a new version.

Expected behavior

It runs the command successfully with no errors.

Actual behavior

I get errors saying that it was unable to unpack to NuGetFallbackFolder:

Permission denied to modify the 'C:\Program Files\dotnet\sdk\NuGetFallbackFolder' folder.

Here are some options to fix this error:
----------------------------------------
1. Re-run this command with elevated access.
2. Disabled the first run experience by setting the environment variable DOTNET_SKIP_FIRST_TIME_EXPERIENCE to true.
3. Copy the .NET Core SDK to a non-protected location and use it from there.

Environment data

dotnet --info output:

.NET Core SDK (reflecting any global.json):
 Version:   2.2.100-preview1-009345
 Commit:    8ca823bfd6

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.17735
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\2.2.100-preview1-009345\

Host (useful for support):
  Version: 2.2.0-preview-26814-03
  Commit:  58b12b9539

.NET Core SDKs installed:
  1.0.0-preview3-004056 [C:\Program Files\dotnet\sdk]
  1.0.4 [C:\Program Files\dotnet\sdk]
  1.1.0 [C:\Program Files\dotnet\sdk]
  2.0.2-vspre-006949 [C:\Program Files\dotnet\sdk]
  2.0.2 [C:\Program Files\dotnet\sdk]
  2.0.3 [C:\Program Files\dotnet\sdk]
  2.1.1-preview-007094 [C:\Program Files\dotnet\sdk]
  2.1.1-preview-007165 [C:\Program Files\dotnet\sdk]
  2.1.1 [C:\Program Files\dotnet\sdk]
  2.1.2 [C:\Program Files\dotnet\sdk]
  2.1.4 [C:\Program Files\dotnet\sdk]
  2.1.100-preview-007326 [C:\Program Files\dotnet\sdk]
  2.1.100-preview-007354 [C:\Program Files\dotnet\sdk]
  2.1.100-preview-007363 [C:\Program Files\dotnet\sdk]
  2.1.100 [C:\Program Files\dotnet\sdk]
  2.1.101 [C:\Program Files\dotnet\sdk]
  2.1.103 [C:\Program Files\dotnet\sdk]
  2.1.104 [C:\Program Files\dotnet\sdk]
  2.1.200-preview-007474 [C:\Program Files\dotnet\sdk]
  2.1.200-preview-007517 [C:\Program Files\dotnet\sdk]
  2.1.200-preview-007576 [C:\Program Files\dotnet\sdk]
  2.1.200-preview-007589 [C:\Program Files\dotnet\sdk]
  2.1.200-preview-007597 [C:\Program Files\dotnet\sdk]
  2.1.200 [C:\Program Files\dotnet\sdk]
  2.1.201 [C:\Program Files\dotnet\sdk]
  2.1.202 [C:\Program Files\dotnet\sdk]
  2.1.300 [C:\Program Files\dotnet\sdk]
  2.1.400-preview-009063 [C:\Program Files\dotnet\sdk]
  2.1.400-preview-009171 [C:\Program Files\dotnet\sdk]
  2.2.100-preview1-009345 [C:\Program Files\dotnet\sdk]

.NET Core runtimes installed:
  Microsoft.AspNetCore.All 2.1.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.1 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.2.0-preview1-34983 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.1.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.1 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.2.0-preview1-34983 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 1.0.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 1.1.2 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.0.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.0.3 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.0.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.0.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.0.7 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.0.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.1 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.2 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.2.0-preview-26814-03 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]

To install additional .NET Core runtimes or SDKs:
  https://aka.ms/dotnet-download

This seems to happen all the time (every time dotnet is updated) and it happens on a few other people's machines as well. Would be good to figure out what's going on.

[livarcocc]

How is dotnet being installed? Msi? Zip?

When prompted for admin permissions, are you allowing it?

The fallback folder should be expanded by the msi during installation. Something is either causing it not to happen or it is happening and we are failing to write the sentinel file that tells us it did happen.

Do you happen to have a DOTNET_SKIP_FIRST_RUN_EXPERIENCE environment variable set to true?

[wli3]

Please continue discussion on https://github.com/dotnet/cli/issues/9807