How to fix “System.InvalidOperationException: PowerShell Gallery is currently unavailable.”

Time needed: 10 minutes.

How to fix “System.InvalidOperationException: PowerShell Gallery is currently unavailable.” in 1 to 5 easy steps

1. Verify whether you have a recent enough PowerShell version

   Run this:
   
   Get-Host | Select-Object Version
   
   If it’s 5.1 or newer, you’re probably good! If not, download latest version here: https://www.microsoft.com/en-us/download/details.aspx?id=54616

2. Verify you have the right repository

   Run this commandlet in your PowerShell:
   
   Get-PSRepository
   
   Your output is somewhat like this:
   
   Name InstallationPolicy SourceLocation
---- ------------------ --------------
PSGallery Untrusted https://www.powershellgallery.com/api/v2
   
   There’s 3 things that COULD be wrong in this case. Depending on the exact error message you got, either:
   1) The source needs to be trusted (see step 3)
   2) The SourceLocation is not accessible (see step 4)
   3) The SourceLocation URI needs to end with ‘/’ (see step 5)

3. Set your PSGallery to be trusted

   Run the following commandlet:
   
   Set-PSRepository -Name "PSGallery" -InstallationPolicy Trusted
   
   If you get an error like this:
   
   Get-PSGalleryApiAvailability : PowerShell Gallery is currently unavailable. Please try again later.
   
   Then you can’t access the URI either because it doesn’t have a trailing slash (see step 5) or because it’s not accessible (see step 4).
   
   And if you get an error like:
   
   Register-PSRepository : Use 'Register-PSRepository -Default' to register the PSGallery repository.
   
   Then, well, run:
   
   Register-PSRepository -Default
   
   To see if it helps!
4. Verify you have access to the URI

   Open up your browser and navigate to this address:
   https://www.powershellgallery.com/api/v2/
   
   If you get something like the screenshot below, you access this address, but your PowerShell can’t.
   
   
   
   In this case your PowerShell is probably unable to access it due to a mismatch in TLS versions – try running this commandlet to enable TLS 1.2 and see if it helps:
   
   [Net.ServicePointManager]::SecurityProtocol = [Net.ServicePointManager]::SecurityProtocol -bor [Net.SecurityProtocolType]::Tls12

5. Fix the PSGallery’s URI

   In case the PSGallery URI does not end with a trailing slash, run the following commands (this’ll set the new PSRepository to be Trusted as well):
   
   Unregister-PSRepository PSGallery
Register-PSRepository -Name PSGallery -SourceLocation "https://www.powershellgallery.com/api/v2/" -InstallationPolicy Trusted
   
   If you get an error after running this, you can also try naming your Repository something else.