New transaction is not allowed because there are other threads running in the session

Question

Getting \"new transaction is not allowed because there are other threads running in the session\".

It has nothing to do with foreach loops or anything people usually

Answer 1

I don't think that this is only problem of not disposed contexts (context doesn't keep opened transaction - you would see it because of uncommitted changes). If you have this problem you most probably don't use the new context instance per request or you have some multi threaded / asynchronous processing on the shared context instance (= one connection). This exception says that multiple threads (probably multiple processed requests) are trying to use their own transaction on the same connection - that is not possible.

Corner case can be manual handling of connections provided to context but I guess you would mention it if you use it.

Edit:

Your factory doesn't provide per request context - it provides single context for all request!!! That static dictionary is shared among all request so the first creates instance and stores it under _DEFAULT key and all other requests will use it.