Azure Cosmos DB
An Azure NoSQL database service for app development.
Azure Cosmos DB for MongoDB: Error 261 (TooManyLogicalSessions) During Initial List Collections Call
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Felix
0
Reputation points
Problem description
I am encountering error 261, labeled as 'TooManyLogicalSessions', when attempting to connect to my Azure Cosmos DB for MongoDB (vCore) resource. This issue occurs during the first call to 'list collections' from a .NET Core application using SDK version 10.x.x. I expected to access the database for development purposes, but the error appears immediately on the initial list collections attempt. The problem started around 2026-09-11T03:04:26Z. I have not observed any open connections at that time and did not find specific guidance for error 261 in the available self-help materials.
Environment
Service: Azure Cosmos DB for MongoDB (vCore); Client: .NET Core application; SDK version: 10.x.x; Operation: listing collections; No specific region, tier/SKU, or resource names provided.
What I've already tried
I have not tried any troubleshooting steps yet.
Current status
I am seeking guidance on resolving the error 261 during the initial list collections call, understanding whether this is related to session limits or configuration issues, and how to mitigate or prevent this error in my development environment. However, I suspect it is a bug in the database.
Azure Cosmos DB
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SIVASANKAR YEDDULA 165 Reputation points Microsoft External Staff Moderator2026-09-11T04:48:16.83+00:00 Hi @Felix ,
Thank you for reaching out to the Microsoft Q&A forum.
To investigate this issue further, I have sent you a private message. Could you please provide the following details through the private message?
Error or failure screenshots
Your email address
Time zone
Your availability for a Microsoft Teams meeting
These details will help us perform a deeper investigation and engage the appropriate engineering team if required.
Once you've shared the requested information, we will continue our analysis and provide further guidance.
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