MongoDB 4.4 stopped getting launched in Windows 10 machine - mongodb

Question

I have installed MongoDB 4.4 on Windows 10 machine, and it was working fine. I could connect it from MongoDB compass. But now when I try to connect, I get 'mongodb compass connect ECONNREFUSED 127.0.0.1:27017' error. So I tried to launch it manually by executing mongod command, and I see following traces:
C:\Program Files\MongoDB\Server\4.4\bin>mongod
{"t":{"$date":"2020-09-17T02:33:16.379-07:00"},"s":"I", "c":"CONTROL", "id":23285, "ctx":"main","msg":"Automatically disabling TLS 1.0, to force-enable TLS 1.0 specify --sslDisabledProtocols 'none'"}
{"t":{"$date":"2020-09-17T02:33:16.383-07:00"},"s":"W", "c":"ASIO", "id":22601, "ctx":"main","msg":"No TransportLayer configured during NetworkInterface startup"}
{"t":{"$date":"2020-09-17T02:33:16.383-07:00"},"s":"I", "c":"NETWORK", "id":4648602, "ctx":"main","msg":"Implicit TCP FastOpen in use."}
{"t":{"$date":"2020-09-17T02:33:16.384-07:00"},"s":"I", "c":"STORAGE", "id":4615611, "ctx":"initandlisten","msg":"MongoDB starting","attr":{"pid":13320,"port":27017,"dbPath":"C:/data/db/","architecture":"64-bit","host":"3INDGHILDIYA1"}}
{"t":{"$date":"2020-09-17T02:33:16.384-07:00"},"s":"I", "c":"CONTROL", "id":23398, "ctx":"initandlisten","msg":"Target operating system minimum version","attr":{"targetMinOS":"Windows 7/Windows Server 2008 R2"}}
{"t":{"$date":"2020-09-17T02:33:16.384-07:00"},"s":"I", "c":"CONTROL", "id":23403, "ctx":"initandlisten","msg":"Build Info","attr":{"buildInfo":{"version":"4.4.1-rc2","gitVersion":"95ea09d61932f51a37a63a10f4d0e0c1fced4723","modules":[],"allocator":"tcmalloc","environment":{"distmod":"windows","distarch":"x86_64","target_arch":"x86_64"}}}}
{"t":{"$date":"2020-09-17T02:33:16.384-07:00"},"s":"I", "c":"CONTROL", "id":51765, "ctx":"initandlisten","msg":"Operating System","attr":{"os":{"name":"Microsoft Windows 10","version":"10.0 (build 17134)"}}}
{"t":{"$date":"2020-09-17T02:33:16.384-07:00"},"s":"I", "c":"CONTROL", "id":21951, "ctx":"initandlisten","msg":"Options set by command line","attr":{"options":{}}}
{"t":{"$date":"2020-09-17T02:33:16.385-07:00"},"s":"E", "c":"STORAGE", "id":20557, "ctx":"initandlisten","msg":"DBException in initAndListen, terminating","attr":{"error":"NonExistentPath: Data directory C:\\data\\db\\ not found. Create the missing directory or specify another path using (1) the --dbpath command line option, or (2) by adding the 'storage.dbPath' option in the configuration file."}}
{"t":{"$date":"2020-09-17T02:33:16.385-07:00"},"s":"I", "c":"REPL", "id":4784900, "ctx":"initandlisten","msg":"Stepping down the ReplicationCoordinator for shutdown","attr":{"waitTimeMillis":10000}}
{"t":{"$date":"2020-09-17T02:33:16.386-07:00"},"s":"I", "c":"COMMAND", "id":4784901, "ctx":"initandlisten","msg":"Shutting down the MirrorMaestro"}
{"t":{"$date":"2020-09-17T02:33:16.386-07:00"},"s":"I", "c":"SHARDING", "id":4784902, "ctx":"initandlisten","msg":"Shutting down the WaitForMajorityService"}
{"t":{"$date":"2020-09-17T02:33:16.387-07:00"},"s":"I", "c":"NETWORK", "id":20562, "ctx":"initandlisten","msg":"Shutdown: going to close listening sockets"}
{"t":{"$date":"2020-09-17T02:33:16.388-07:00"},"s":"I", "c":"NETWORK", "id":4784905, "ctx":"initandlisten","msg":"Shutting down the global connection pool"}
{"t":{"$date":"2020-09-17T02:33:16.389-07:00"},"s":"I", "c":"STORAGE", "id":4784906, "ctx":"initandlisten","msg":"Shutting down the FlowControlTicketholder"}
{"t":{"$date":"2020-09-17T02:33:16.401-07:00"},"s":"I", "c":"-", "id":20520, "ctx":"initandlisten","msg":"Stopping further Flow Control ticket acquisitions."}
{"t":{"$date":"2020-09-17T02:33:16.412-07:00"},"s":"I", "c":"NETWORK", "id":4784918, "ctx":"initandlisten","msg":"Shutting down the ReplicaSetMonitor"}
{"t":{"$date":"2020-09-17T02:33:16.413-07:00"},"s":"I", "c":"SHARDING", "id":4784921, "ctx":"initandlisten","msg":"Shutting down the MigrationUtilExecutor"}
{"t":{"$date":"2020-09-17T02:33:16.424-07:00"},"s":"I", "c":"CONTROL", "id":4784925, "ctx":"initandlisten","msg":"Shutting down free monitoring"}
{"t":{"$date":"2020-09-17T02:33:16.428-07:00"},"s":"I", "c":"FTDC", "id":4784926, "ctx":"initandlisten","msg":"Shutting down full-time data capture"}
{"t":{"$date":"2020-09-17T02:33:16.429-07:00"},"s":"I", "c":"STORAGE", "id":4784927, "ctx":"initandlisten","msg":"Shutting down the HealthLog"}
{"t":{"$date":"2020-09-17T02:33:16.437-07:00"},"s":"I", "c":"STORAGE", "id":4784929, "ctx":"initandlisten","msg":"Acquiring the global lock for shutdown"}
{"t":{"$date":"2020-09-17T02:33:16.442-07:00"},"s":"I", "c":"-", "id":4784931, "ctx":"initandlisten","msg":"Dropping the scope cache for shutdown"}
{"t":{"$date":"2020-09-17T02:33:16.449-07:00"},"s":"I", "c":"CONTROL", "id":20565, "ctx":"initandlisten","msg":"Now exiting"}
{"t":{"$date":"2020-09-17T02:33:16.450-07:00"},"s":"I", "c":"CONTROL", "id":23138, "ctx":"initandlisten","msg":"Shutting down","attr":{"exitCode":100}}
What can be the reason here?
In config file storage.dbpath is set to 'C:\Program Files\MongoDB\Server\4.4\data'.
# Where and how to store data.
storage:
dbPath: C:\Program Files\MongoDB\Server\4.4\data

Answer 1

NonExistentPath: Data directory C:\\data\\db\\
You need to create that folder. Or change it in a config file and use this file:
mongod --config mongod.conf
Keep in mind that this folder must be writable for the user who is running mongod.