Upgrade MongoDB 4.x -> 5, MacOS, ECONNREFUSED 127.0.0.1:27017

[Cezary_Tomczyk]

Hello.

Just upgraded MongoDB on macOS Big Sur from v4 to v5 and now I can’t connect to MongoDB. Got following issue:

MongoDB shell version v5.0.0
connecting to: mongodb://127.0.0.1:27017/?compressors=disabled&gssapiServiceName=mongodb
Error: couldn’t connect to server 127.0.0.1:27017, connection attempt failed: SocketException: Error connecting to 127.0.0.1:27017 :: caused by :: Connection refused :
connect@src/mongo/shell/mongo.js:372:17
@(connect):2:6
exception: connect failed
exiting with code 1

I use brew. Also, from the logs I see:

“msg”:“Wrong mongod version”,“attr”:{“error”:"UPGRADE PROBLEM: Found an invalid featureCompatibilityVersion document (ERROR: Location4926900: Invalid featureCompatibilityVersion document in admin.system.version: { _id: "featureCompatibilityVersion", version: "4.2" }

docs.mongodb.com/v5.0/release-notes/4.4/#upgrade-procedures doesn’t help for me as even MongoDB is not running.

Running in terminal: ps -ef | grep mongod gives a feedback that mongod is not running.

How do I change the value of featureCompatibilityVersiondocument when MongoDB is not running? I guess first would be good to resolve Connection Refused issue.

I am getting stuck now where to look. Any tip would be much appreciated.

[Cezary_Tomczyk]

Adding info that running mongo-community through brew gave me:

==> Successfully stopped mongodb-community (label: homebrew.mxcl.mongodb-community)
==> Successfully started mongodb-community (label: homebrew.mxcl.mongodb-community)

[Cezary_Tomczyk]

Seems the only way to resolve issue was to:

1. Create backup of the content specified under dbPath from mongod.conf.
2. Stop mongodb-community (brew services stop mongodb-community).
3. Remove whole content specified under dbPath. In my case it was: /usr/local/var/mongodb.
4. Restart the computer (just in case).

Then MongoDB started working. Since I didn’t have anything important to me it is fine, but it would be good to get some quick feedback on how to restore previously backed up data.

Hope this helps someone.