Getting the server response when Invoke-Webrequest results in error 5xx

Hi there,

lately, I’ve been confronted with a problem where I simply couldn’t get meaningful error messages from failing runs of Invoke-Webrequest. In doing something like this:

    Try {
        log "Creating new session token for $Url"
        $result = Invoke-WebRequest -uri $Url -Headers $headers -Method GET 
    }
    Catch {
        $err = $_.Exception.Message

Try {

log "Creating new session token for $Url"

$result = Invoke-WebRequest -uri $Url -Headers $headers -Method GET

}

Catch {

$err = $_.Exception.Message

$err would only ever contain the error code like “500 bla”, but not what the server actually returned as the error message. I was querying a REST API.

A colleague finally found the answer here.

What needs to be done is, to tell Powershell to read the stream. The exact difference I cannot tell, as this happens only for 5xx errors, as far as I can see.

   Catch {
        $error = $_.Exception.Message
        $error2 = $_.Exception.Response.GetResponseStream()
        $stream = New-Object System.IO.StreamReader($error2)
        $response = $stream.ReadToEnd();
    }

Catch {

$error = $_.Exception.Message

$error2 = $_.Exception.Response.GetResponseStream()

$stream = New-Object System.IO.StreamReader($error2)

$response = $stream.ReadToEnd();

}

$response will now contain the body of what the remote web service returned.

This is another good case that shows me, how easily one can get lost doing g**gle searches. I had searched for a solution also, but the sheer mass of results has overwhelmed me. Also, using only slightly different search terms always give totally different search results… Maybe I was using the wrong terms… Maybe I should have also read the documentation for Invoke-Webrequest more closely 🙂

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