dotnet/wpf · error · PrintServerException

PrintSystemException.PrintServer.DeleteConnection

Error message

PrintSystemException.PrintServer.DeleteConnection

What it means

Thrown when disconnecting from a network print queue by path fails. ThunkDeletePrinterConnection calls the Win32 DeletePrinterConnection API; any spooler error is wrapped in a PrintSystemException with the DeleteConnection key.

Solutions

Check the connection exists first via GetPrintQueues / net use before calling DisconnectFromPrintQueue.
Use the exact same path string used when the connection was added (same server name form).
Remember connections are per-user: run in the same user context that created the connection.
Inspect the inner HResult for the specific Win32 error.

Example fix

// before: blind disconnect
server.DisconnectFromPrintQueue(@"\\printserver\LaserJet");
// after: only disconnect existing connections
if (server.GetPrintQueues().Any(q => q.FullName == @"\\printserver\LaserJet"))
    server.DisconnectFromPrintQueue(@"\\printserver\LaserJet");

Defensive patterns

Strategy: validation

Validate before calling

bool isConnected = server.GetPrintQueues().Any(q => q.FullName == printQueuePath);
if (!isConnected) return; // nothing to disconnect

Type guard

static bool IsConnected(LocalPrintServer server, string path) =>
    server.GetPrintQueues().Any(q => q.FullName == path);

Try / catch

try { server.DisconnectFromPrintQueue(path); }
catch (PrintSystemException ex)
{
    logger.LogWarning("Disconnect failed for {Path}: {HResult}", path, ex.InnerException?.HResult);
}

Prevention

Only disconnect connections you previously created in the same user session
Use the exact path string used at connect time
Treat disconnect failures as non-fatal in cleanup code

When it happens

Trigger: Calling LocalPrintServer.DisconnectFromPrintQueue(printQueuePath) for a path that was never connected, is misspelled, or where the connection is held by another process/session the caller cannot modify.

Common situations: Trying to disconnect a queue that doesn't exist in the user's connections; deleting connections per-machine vs per-user confusion (connections are per-user); path casing/server alias mismatches (FQDN vs NetBIOS name).

Understand the failure class

Background: 'Could not be found', 'does not exist', 'not found in database': the resource-not-found family when an ID, slug, key, or URI lookup comes back empty — this error's family across 20 libraries.

Related errors

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/d0c3d461a79da171. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/System.Printing/CPP/src/LocalPrintServer.cpp:590

--*/
bool
LocalPrintServer::
DisconnectFromPrintQueue(
    String^ printQueuePath
    )
{
    VerifyAccess();

    bool    returnValue = false;

    try
    {
        returnValue = PrintWin32Thunk::PrinterThunkHandler::ThunkDeletePrinterConnection(printQueuePath);
    }
    catch (InternalPrintSystemException^ internalException)
    {
        throw CreatePrintServerException(internalException->HResult, "PrintSystemException.PrintServer.DeleteConnection");
    }

    return returnValue;
}

/*++

Routine Name:

    DisconnectFromPrintQueue

Routine Description:

    Deletes a printer connection to a given printer.

Arguments:

    printerPath   - \\server\share or \\server\printerName

View on GitHub (pinned to 81131a70a4)