Everyone Using DbContext Concurrently Is Making This Mistake

I Googled it. I asked AI. I tried every Stack Overflow answer I could find. Nothing worked. Then I found the fix completely by accident — in a book I wasn't even reading for that reason. Here's what was actually going on — explained simply enough that even if you're new to .NET, you'll get it immediately. What I Was Trying to Do I was working on a feature that needed to call two different API operations at the same time — concurrently. Run both, wait for both to finish, move on. Simple enough in theory. Except the moment I did, my app threw this: InvalidOperationException: A second operation was started on this context instance before a previous operation completed. This is usually caused by different threads using the same instance of DbContext. I stared at it. Searched for it. Tried things for hours. Nothing matched my exact situation. I almost scrapped the whole concurrent approach and just ran them one after the other. Then completely by accident — r