how to solve Exception:Call was rejected by callee. (Exception from HRESULT: 0x80010001 (RPC_E_CALL_REJECTED)) in C#?

I ran into this same error being thrown when I deployed my application onto a machine without a fully activated and licensed installation of Excel. I spent hours trying to diagnose the issue. Make sure you check your Office installations to make sure they are complete.

I solved this behaviour with the help of this question:

Strange behaviour of "Call was rejected by callee." exception with Excel

The issue was simply that the Workbook.Open hadn't finished when I gave a Worksheet.SaveAs command. So sometimes, the script would work, sometimes not.

I simply added a pause in the script after Workbook.Open and it worked. I went on to find a property Ready, which allowed me to do exactly what I wanted:

    $excel = New-Object -ComObject "Excel.Application" -ea Stop
    $wb = $excel.Workbooks.Open($workbook)
    $sheet = $wb.Sheets("List")
    while (-not $excel.Ready) {
        sleep 1
    }
    $sheet.SaveAs($csvpath,6)

So in my case, it had nothing to do with non-activated or corrupted Excel installations.

Ensure that MS Word/Excel is not showing a dialog box that needs a response.

I set a breakpoint on the line that caused the failure, then set .Visible to true in PowerShell, to find this:

$word.Visible = $true

After I clicked 'Yes' and updated the settings, after I re-ran my scripted COM interactions, they succeeded.