Enabling MongoDB replication to solve this error when running transactions: "MongoServerError: Transaction numbers are only allowed on a replica set member or mongos".

Enabling MongoDB Replication.md

Enabling MongoDB Replication

1. Stop Mongod Service/Daemon/Process.

2. Find & open the mongod.conf.

   • Windows: <MongoDB-Server-Bin-Path>/mongod.conf
   • Linux: /etc/mongod.conf

3. Add the following to the File:

replication:
   oplogSizeMB: 5000 # <-- Usual Value could be: 5% of Free-Disk-Space | Min: 990 | Max: 50000 
   replSetName: local-rs
   enableMajorityReadConcern: true

4. Start the Mongod Service/Daemon/Process.

5. Run MongoDB Shell using mongosh.

6. Run:

rs.initiate()

7. Now when connecting to your mongod instance make use of the replSet parameter:
   • Local MongoDB Compass Example: mongodb://localhost:27017/?replicaSet=local-rs&readPreference=primary
   • mongosh seems to work without that option.