Powershell CSOM folder.Files.Add(FileCreationInformation) Working earlier, Fails now?

Question

Using Powershell and CSOM, on Sharepoint Online, I have successfully upoaded 300K pdf files w/metadata into folders in document libraries.

Today, though, the same code is failing to Add files...

Snippets of code follow:

#Get File Collection for folder
$Files = $folder.Files
$context.Load($Files)
$context.ExecuteQuery()

try 
{
    # Setup FileStream and FileInfo
    $FileStream = New-Object IO.FileStream($SrcFilePath,[System.IO.FileMode]::Open)
    $FileCreationInfo = New-Object Microsoft.SharePoint.Client.FileCreationInformation
    $FileCreationInfo.Overwrite = $true
    $FileCreationInfo.ContentStream = $FileStream
    $FileCreationInfo.URL = $folderUrl + '/' + $_.SedaID

    # Upload FIle
    $Upload = $Files.Add($FileCreationInfo)
    $context.Load($Upload)
    $context.Load($Upload.ListItemAllFields)
    $context.ExecuteQuery()

    # Update Metadata
    Set-SPOListItem -List $listTitle -Identity $($Upload.ListItemAllFields.Id) `
        -ContentType "SEDA Document" -Values $Metadata
}
Catch
{
    $ErrorMessage = $_.Exception.Message
    $ItemFailed = $true
    $FailCount += 1

    “$Time : Error Uploading {0}:`t   {1}" -f $_.SedaID, $ErrorMessage | out-file $ErrorFile -append

}

$Filestream appears legit:

$FileCreationInfo appears legit:

But folder.Files.Add(FileCreationInfo) now Errors like this:

Any idea what I am doing wrong this time?

Answer 1

After confirming that all of the code was correct, and experiencing multiple, unrelated errors (invalid cast errors, out-of-memory, etc.), I decided to uninstall/reinstall WMF 5 (w/powershell 5) and reinstall the latest Sharepoint Online Client assemblies, and my application worked flawlessly! I'm not sure what caused the corruption(s) in the platform, but one area I know could be improved, and that's the error messaging across the entire Microsoft 'echosystem'... There was no clue whatsoever!