‘Cannot Access a closed file’ error on some files

I’m getting Cannot Access a closed file on some files when I try to upload them. I’m creating a small web app, when a user creates an account on the website, they are required to upload a file. Once they have uploaded the file, I should see it in MongoDB. The issue is some files are uploaded successfully while others create errors. This is the exact error msg from the log:

System.ObjectDisposedException: Cannot access a disposed object, ASP.NET Core 3.1

I am writing an API using SignalR in ASP.NET Core 3.1. I am totally new to .NET Core, and am pretty new to SignalR too. I am having an issue executing MongoDB (Atlas) queries which are running in transactions. It appears that the transaction sessions are expiring before the queries are executing. I’m quite sure it’s a async/await issue, but don’t seem to be able to fix it.

How to return multiple values from a request using FastAPI?

I’m trying to create an API using FastAPI + MongoDB that can return multiple values from the request. The MongoDB is full of data and using mongoengine I can consult one or all data when sending a request to the specific endpoint.
What I’m trying to do now is receive one or more data from an endpoint, for example: