Issues about Chunkupload

The documentation for UploadSessionLookupError.IncorrectOffset covers an example of how this can occur:

"The specified offset was incorrect. See the value for the correct offset. This error may occur when a previous request was received and processed successfully but the client did not receive the response, e.g. due to a network error."

To get the correct offset, you can catch and inspect the exception like this:

try {
    await client.Files.UploadSessionAppendV2Async(cursor, body: memStream);
} catch (ApiException<UploadSessionLookupError> e) {

    if (e.ErrorResponse.IsIncorrectOffset) {
        Console.WriteLine("Expected offset: " + e.ErrorResponse.AsIncorrectOffset.Value.CorrectOffset);
    }
    // todo: other error handling
    throw;
}

In your 5120kb file scenario, I believe the offset would still be 3072 at that point, since the connection failed. However that may depend on the exact nature of the failure, so you should always check the returned value anyway.