Powershell v3 Invoke-WebRequest HTTPS error

Using Powershell v3's Invoke-WebRequest and Invoke-RestMethod I have succesfully used the POST method to post a json file to a https website.

The command I'm using is

 $cert=New-Object System.Security.Cryptography.X509Certificates.X509Certificate2("cert.crt")
 Invoke-WebRequest -Uri https://IPADDRESS/resource -Credential $cred -certificate $cert -Body $json -ContentType application/json -Method POST

However when I attempt to use the GET method like:

 Invoke-WebRequest -Uri https://IPADDRESS/resource -Credential $cred -certificate $cert -Method GET

The following error is returned

 Invoke-RestMethod : The underlying connection was closed: An unexpected error occurred on a send.
 At line:8 char:11
 + $output = Invoke-RestMethod -Uri https://IPADDRESS/resource -Credential $cred
 +           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo          : InvalidOperation: (System.Net.HttpWebRequest:HttpWebRequest)      [Invoke-RestMethod], WebException
+ FullyQualifiedErrorId : WebCmdletWebResponseException,Microsoft.PowerShell.Commands.InvokeRestMethodCommand

I have attempted using the following code to ignore SSL cert, but I'm not sure if its actually doing anything.

 [System.Net.ServicePointManager]::ServerCertificateValidationCallback = {$true}

Can someone provide some guideance on what might be going wrong here and how to fix it?

Thanks

This work-around worked for me: http://connect.microsoft.com/PowerShell/feedback/details/419466/new-webserviceproxy-needs-force-parameter-to-ignore-ssl-errors

Basically, in your PowerShell script:

add-type @"
    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;
        }
    }
"@
[System.Net.ServicePointManager]::CertificatePolicy = New-Object TrustAllCertsPolicy

$result = Invoke-WebRequest -Uri "https://IpAddress/resource"

Lee's answer is great, but I also had issues with which protocols the web server supported.
After also adding the following lines, I could get the https request through. As pointed out in this answer https://stackoverflow.com/a/36266735

$AllProtocols = [System.Net.SecurityProtocolType]'Ssl3,Tls,Tls11,Tls12'
[System.Net.ServicePointManager]::SecurityProtocol = $AllProtocols

My full solution with Lee's code.

add-type @"
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;
    }
}
"@
$AllProtocols = [System.Net.SecurityProtocolType]'Ssl3,Tls,Tls11,Tls12'
[System.Net.ServicePointManager]::SecurityProtocol = $AllProtocols
[System.Net.ServicePointManager]::CertificatePolicy = New-Object TrustAllCertsPolicy

An alternative implementation in pure powershell (without Add-Type of c# source):

#requires -Version 5
#requires -PSEdition Desktop

class TrustAllCertsPolicy : System.Net.ICertificatePolicy {
    [bool] CheckValidationResult([System.Net.ServicePoint] $a,
                                 [System.Security.Cryptography.X509Certificates.X509Certificate] $b,
                                 [System.Net.WebRequest] $c,
                                 [int] $d) {
        return $true
    }
}
[System.Net.ServicePointManager]::CertificatePolicy = [TrustAllCertsPolicy]::new()

Did you try using System.Net.WebClient?

$url = 'https://IPADDRESS/resource'
$wc = New-Object System.Net.WebClient
$wc.Credentials = New-Object System.Net.NetworkCredential("username","password")
$wc.DownloadString($url)

Invoke-WebRequest "DomainName" -SkipCertificateCheck

You can use -SkipCertificateCheck Parameter to achieve this as a one-liner command ( THIS PARAMETER IS ONLY SUPPORTED ON CORE PSEDITION )