File Search file upload problem with CosmosDB

[marekpukaj]

What happened?

Prerequisites:
Connect Librechat to Azure CosmosDB Mongo-compatible engine.

Problem:
When you create a brand new agent with file search capability, and when you upload multiple files, let's say 4 upload batches, each containing 10 files, you will run into the error similar to this one:
[/files] Error processing file: Size 32523176 is larger than MaxDocumentSize 16777216
The error indicates that the document size of the MongoDB document exceeds 16 MB.
After some investigation, I assume this problem is caused by concurrent calls to the upload endpoint, which in the background, updates the agent document. The problem seems to be caused by the method addAgentResourceFile in file Agent.js, specifically by addToSet update.

Version Information

aec1777

Steps to Reproduce

1. Connect Librechat to CosmosDB DB
2. Create new agent with file search capability
3. Upload multiple files - 4 upload batches with 10 files
4. You should see the error

What browsers are you seeing the problem on?

No response

Relevant log output

2025-07-22 11:37:34 error: [/files] Error processing file: Size 32523131 is larger than MaxDocumentSize 16777216
2025-07-22 11:39:18 error: [/files] Error processing file: Size 32523176 is larger than MaxDocumentSize 16777216
2025-07-22 11:40:18 error: [/files] Error processing file: Size 32523176 is larger than MaxDocumentSize 16777216
2025-07-22 11:40:19 error: [/files] Error processing file: Size 32523176 is larger than MaxDocumentSize 16777216
2025-07-22 11:40:29 error: [/files] Error processing file: Size 32523176 is larger than MaxDocumentSize 16777216
2025-07-22 11:40:34 error: [/files] Error processing file: Size 32523176 is larger than MaxDocumentSize 16777216
2025-07-22 11:41:12 error: [/files] Error processing file: Size 32523176 is larger than MaxDocumentSize 16777216

Screenshots

No response

Code of Conduct

• I agree to follow this project's Code of Conduct

[danny-avila]

The problem seems to be caused by the method addAgentResourceFile in file Agent.js, specifically by addToSet update.

It's very unusual these methods would cause it, as they don't add significant data to either the agent document or files collection.

Error logs with stack traces would be helpful here:

Log locations:

• Docker: Project root directory ./logs
• npm: ./api/logs

There are two types of logs that can help diagnose the issue:

• debug logs (debug-YYYY-MM-DD.log)
• error logs (error-YYYY-MM-DD.log)

Error logs contain exact stack traces and are especially helpful, but both can provide valuable information.

Please only include the relevant portions of logs that correspond to when you reproduced the error.

Also if you can share the files used, really any files that help reproduce the error, would be helpful.

[marekpukaj]

Thank you for a quick reply. I had the same thought. There is nothing unusual about these methods. However, I debugged the flow using the debugger with breakpoints placed in these methods, and it really seems like these are causing the problem. I think the problem might be caused by the fact that I am uploading multiple files in parallel, meaning FE will trigger multiple POST /files requests at once, and CosmosDB will allocate some additional space for deduplication when doing addAgentResourceFile .

Here are the log files but there is no additional information that would help me to pinpoint the problem.

debug logs:

...
2025-07-22T17:29:07.375Z debug: File processed successfully.
{
  status: true,
  file_id: "8c2b6005-b4e7-4d22-80e8-eb7b78519b47",
  filename: "file1.pdf",
  known_type: true,
}
2025-07-22T17:29:08.415Z debug: File processed successfully.
{
  status: true,
  file_id: "f8dcc8cd-8433-4cc8-b7a4-68b2988bcacb",
  filename: "file2.pdf",
  known_type: true,
}
2025-07-22T17:29:18.460Z error: [/files] Error processing file: Size 32522338 is larger than MaxDocumentSize 16777216

error logs:

{
  "code": 17419,
  "codeName": "DocumentAfterUpdateLargerThanMaxSize",
  "errorLabelSet": {},
  "errorResponse": {
    "code": 17419,
    "codeName": "DocumentAfterUpdateLargerThanMaxSize",
    "errmsg": "Size 32522248 is larger than MaxDocumentSize 16777216",
    "ok": 0
  },
  "level": "error",
  "message": "[/files] Error processing file: Size 32522248 is larger than MaxDocumentSize 16777216",
  "ok": 0,
  "stack": "MongoServerError: Size 32522248 is larger than MaxDocumentSize 16777216\n    at Connection.sendCommand (/librechat/api/node_modules/mongodb/lib/cmap/connection.js:299:27)\n    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)\n    at async Connection.command (/librechat/api/node_modules/mongodb/lib/cmap/connection.js:327:26)\n    at async Server.command (/librechat/api/node_modules/mongodb/lib/sdam/server.js:168:29)\n    at async FindOneAndUpdateOperation.executeCommand (/librechat/api/node_modules/mongodb/lib/operations/command.js:76:16)\n    at async FindOneAndUpdateOperation.execute (/librechat/api/node_modules/mongodb/lib/operations/find_and_modify.js:85:24)\n    at async tryOperation (/librechat/api/node_modules/mongodb/lib/operations/execute_operation.js:207:20)\n    at async executeOperation (/librechat/api/node_modules/mongodb/lib/operations/execute_operation.js:75:16)\n    at async Collection.findOneAndUpdate (/librechat/api/node_modules/mongodb/lib/collection.js:500:16)\n    at async model.Query._findOneAndUpdate (/librechat/api/node_modules/mongoose/lib/query.js:3477:13)"
}