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

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

    # 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)

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

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


$Filestream appears legit:

enter image description here

$FileCreationInfo appears legit:

enter image description here

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

enter image description here

Any idea what I am doing wrong this time?