Microsoft.Azure.Cosmos.Table POST requests to https://<account>.table.core.windows.net:443/Tables() failing with 409

Question

Hello,

A function app written with dotnet 3.1, that uses Microsoft.Azure.Cosmos.Table Version="1.0.8" keeps posting requests to https://<account>.table.core.windows.net:443/Tables(), failing with 409, even if it's a scenario in which I am not accessing the Azure storage tables at all.

 public async Task AnOrchestration(
           [DurableClient] IDurableOrchestrationClient client,
           ILogger log,
           [Table("CalloutsTable")] CloudTable cloudTable)
        {
                var idList = await GetList....(params);

                foreach (var x in idList)
                {
                    doSomething...();

                    await 
                        cloudTable.ExecuteAsync(TableOperation.Insert(idList+others));
                }
        }

When the list is empty, that foreach is not executed, so no insert to be done.
But still, the client library tries a POST failing with 409.

I have noticed an older post here 42, saying that

'this seems to be expected behavior for the client library 8+ CloudTable.CreateIfNotExists throws a 409 error and moves on if the table already exists.'

I mention that my table already exists, is not created dynamically via the app.

Is this the usual behavior of Azure.Cosmos.Table 1.0.8?

Thank you!

Answer 1

Hello @adriana_malea - The error probably isn't caused by the Insert() statement in your foreach() loop. This appears to be a known issue around the behavior of CloudTable.CreateIfNotExists() where it tries to create the table first, and if there's an existing table, it'll return the 409 which is a “The specified entity already exists” error... as opposed to checking for an existing table first and attempting to create it only if there isn't one.

Here're a couple of resources:

• https://github.com/Azure/azure-sdk-for-net/issues/28084
• Helpful blog post: https://brewgrammer.com/Beware-Of-CreateIfNotExists/

It looks like you're using Durable Functions. Are you calling the CloudTable.CreateIfNotExists() somewhere?

All in all, the error appears to be harmless but makes a lot of noise in telemetries and is expected to be fixed in the next SDK release.

I hope this is helpful, if any further questions, just let me know.

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