After using standard solutions for ignoring certificate verification, Invoke-RestMethod
is returning:
Invoke-RestMethod : A system error occurred and has been logged. Please try again later or contact your administrator.
I just noticed this failure today, so I think it has something to do with a Powershell update. By "standard solutions" I mean:
[System.Net.ServicePointManager]::ServerCertificateValidationCallback = { $true }
which stopped working a few months ago, and setting the callback properly in a C# type added to Powershell (description below in History).
Here is my environment:
> $PSVersionTable
Name Value
---- -----
PSVersion 5.1.15063.674
PSEdition Desktop
PSCompatibleVersions {1.0, 2.0, 3.0, 4.0...}
BuildVersion 10.0.15063.674
CLRVersion 4.0.30319.42000
WSManStackVersion 3.0
PSRemotingProtocolVersion 2.3
SerializationVersion 1.1.0.1
Here is a little history so this question doesn't just get closed as a duplicate.
If you Google around or search StackOverflow you can find this question coming up with a few canned responses. However, today I noticed that all of the standard solutions aren't working anymore.
The standard error Powershell gives is:
Invoke-RestMethod : The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel.
The standard answer given on forums everywhere is to use this command before you call Invoke-RestMethod
:
[System.Net.ServicePointManager]::ServerCertificateValidationCallback = { $true }
But if you're using an up to date version of Windows 10 / 2016 and Powershell, then your call to Invoke-RestMethod
will return:
Invoke-RestMethod : The underlying connection was closed: An unexpected error occurred on a send.
The explanation for why that happens is found on Huddled Masses blog. It can be summarized as:
Setting the ServerCertificateValidationCallback to a scriptblock won't work for an asynchronous callback (one that happens on a task thread), because the other thread won't have a runspace to execute the script on.
Originally, I had been solving that problem with this code:
if (-not ([System.Management.Automation.PSTypeName]"TrustAllCertsPolicy").Type)
{
Add-Type -TypeDefinition @"
using System.Net;
using System.Security.Cryptography.X509Certificates;
public class TrustAllCertsPolicy : ICertificatePolicy {
public bool CheckValidationResult(
ServicePoint srvPoint, X509Certificate certificate,
WebRequest request, int certificateProblem)
{
return true;
}
}
"@
}
if ([System.Net.ServicePointManager]::CertificatePolicy.ToString() -ne "TrustAllCertsPolicy")
{
[System.Net.ServicePointManager]::CertificatePolicy = New-Object TrustAllCertsPolicy
}
But, that didn't work on Windows Server 2016, even though it was working fine on Windows 10. So, based on Huddled Masses I wrote this up to handle certificate validation callbacks in C# rather than a script block:
function Disable-SslVerification
{
if (-not ([System.Management.Automation.PSTypeName]"TrustEverything").Type)
{
Add-Type -TypeDefinition @"
using System.Net.Security;
using System.Security.Cryptography.X509Certificates;
public static class TrustEverything
{
private static bool ValidationCallback(object sender, X509Certificate certificate, X509Chain chain,
SslPolicyErrors sslPolicyErrors) { return true; }
public static void SetCallback() { System.Net.ServicePointManager.ServerCertificateValidationCallback = ValidationCallback; }
public static void UnsetCallback() { System.Net.ServicePointManager.ServerCertificateValidationCallback = null; }
}
"@
}
[TrustEverything]::SetCallback()
}
function Enable-SslVerification
{
if (([System.Management.Automation.PSTypeName]"TrustEverything").Type)
{
[TrustEverything]::UnsetCallback()
}
}
That worked really well for a long time, but just recently I started getting the following error back when I call Invoke-RestMethod
:
Invoke-RestMethod : A system error occurred and has been logged. Please try again later or contact your administrator.
I understand that a proper solution is just to deploy certificates, but often you just want to test things out without having to set up a proper PKIX.
I think I have narrowed this down to a change in the web service that I'm calling. Doh!
The Disable-SslVerification
and Enable-SslVerification
function that I listed in my question are still the best way to go and seem to work.
I look forward to the -SkipCertificateCheck
switch mentioned by Bacon Bits in the comments. Then, we can stop hacking. =)
Hopefully this question is valuable for people who are trying to solve the same problem but run into the An unexpected error occurred on a send
problem.