Uploaded attachment PNG is not shown correctly

I use the following powershell and REST-API to upload attachment

class TfsHelper{
#...
  [string]UploadPng([string]$TfsProject, [string]$PngFileName) {
    $uri = "http://$organization/$TfsProject/_apis/wit/attachments?fileName=image.png&api-version=5.1"
    $strPngBase64 = [convert]::ToBase64String((Get-Content $PngFileName -Encoding byte))  
    $rtn = Invoke-RestMethod -Uri $uri -Method POST -Headers $this.Header `
      -Body $strPngBase64 `
      -ContentType 'application/octet-stream'
    return $rtn.url
  }
}

The function UploadPng executed successfu开发者_StackOverflow中文版lly and I can also get the response which contains the uploaded PNG url and uuid

But when I opened response url in browser to check the uploaded PNG, I found the uploaded image was not shown as expected and not same as the original one.

So, what`s wrong with the function UploadPng?

I can reproduce the same issue when using the same Powershell script.

To solve this issue, you can use the powershell command: [IO.File]::ReadAllBytes("$PngFileName") to read the file and no need to convert it to base64. Then you can change the content type to application/json.

class TfsHelper{
#...
  [string]UploadPng([string]$TfsProject, [string]$PngFileName) {
    $uri = "http://$organization/$TfsProject/_apis/wit/attachments?fileName=image.png&api-version=5.1"
    $file = [IO.File]::ReadAllBytes("$PngFileName") 
    $rtn = Invoke-RestMethod -Uri $uri -Method POST -Headers $this.Header `
      -Body $file  `
      -ContentType 'application/json'
    return $rtn.url
  }
}

Or you can use the -InFile to create the attachment.

Here is PowerShell example:

class TfsHelper{
#...
  [string]UploadPng([string]$TfsProject, [string]$PngFileName) {
    $uri = "http://$organization/$TfsProject/_apis/wit/attachments?fileName=image.png&api-version=5.1"
    $file = Get-ChildItem -Path "filepath" 
    $rtn = Invoke-RestMethod -Uri $uri -Method POST -Headers $this.Header `
      -InFile $file `
      -ContentType 'application/octet-stream'
    return $rtn.url
  }
}

Update:

class TfsHelper{
  [string]UploadPng([string]$TfsProject, [string]$PngFileName) {
    $uri = "https://dev.azure.com/orgname/$TfsProject/_apis/wit/attachments?fileName=image.png&api-version=5.1"
    $file = Get-ChildItem -Path "$PngFileName" 
    $token = "PAT"
    $token = [System.Convert]::ToBase64String([System.Text.Encoding]::ASCII.GetBytes(":$($token)"))
    $rtn = Invoke-RestMethod -Uri $uri -Method POST -Headers @{Authorization = "Basic $token"} `
      -InFile $file `
      -ContentType 'application/octet-stream'

    return $rtn.url
  }
}


$uploadpng = [TfsHelper]::new()

echo $uploadpng.UploadPng("projectname","pngpath")