MeteorJS Oplog: Got exception while polling query MongoError: no primary server available

we needed to duplicate a legacy meteorJS app recently, onto a new server and a new database.So we cloned the server, created a new database and pointed the cloned server to the new database.

The meteorJS app works, everything appears fine.

However we noticed that the logs is showing error like MongoError: no primary server available, everytime when restarting:

2024-02-01T06:37:06.151478+00:00 heroku[web.1]: Restarting2024-02-01T06:37:06.217824+00:00 heroku[web.1]: State changed from up to starting2024-02-01T06:37:06.969254+00:00 heroku[web.1]: Stopping all processes with SIGTERM2024-02-01T06:37:07.074219+00:00 heroku[web.1]: Process exited with status 1432024-02-01T06:37:45.658856+00:00 heroku[web.1]: Starting process with command `.meteor/heroku_build/bin/node $NODEJS_PARAMS .meteor/heroku_build/app/main.js`2024-02-01T06:38:00.149936+00:00 app[web.1]: Got exception while polling query MongoError: no primary server available2024-02-01T06:38:00.149991+00:00 app[web.1]:     at ReplSetState.pickServer (/app/.meteor/heroku_build/app/programs/server/npm/node_modules/meteor/npm-mongo/node_modules/mongodb/lib/core/topologies/replset_state.js:780:12)2024-02-01T06:38:00.149991+00:00 app[web.1]:     at Timeout._selectServer [as _onTimeout] (/app/.meteor/heroku_build/app/programs/server/npm/node_modules/meteor/npm-mongo/node_modules/mongodb/lib/core/topologies/replset.js:1142:43)2024-02-01T06:38:00.149992+00:00 app[web.1]:     at listOnTimeout (internal/timers.js:549:17)2024-02-01T06:38:00.149992+00:00 app[web.1]:     at processTimers (internal/timers.js:492:7)2024-02-01T06:38:00.149993+00:00 app[web.1]:  => awaited here:2024-02-01T06:38:00.149993+00:00 app[web.1]:     at Function.Promise.await (/app/.meteor/heroku_build/app/programs/server/npm/node_modules/meteor/promise/node_modules/meteor-promise/promise_server.js:56:12)2024-02-01T06:38:00.149994+00:00 app[web.1]:     at packages/mongo/mongo_driver.js:1073:142024-02-01T06:38:00.149994+00:00 app[web.1]:     at /app/.meteor/heroku_build/app/programs/server/npm/node_modules/meteor/promise/node_modules/meteor-promise/fiber_pool.js:43:402024-02-01T06:38:00.149994+00:00 app[web.1]:  => awaited here:2024-02-01T06:38:00.149995+00:00 app[web.1]:     at Promise.await (/app/.meteor/heroku_build/app/programs/server/npm/node_modules/meteor/promise/node_modules/meteor-promise/promise_server.js:60:12)2024-02-01T06:38:00.149995+00:00 app[web.1]:     at SynchronousCursor._nextObject (packages/mongo/mongo_driver.js:1122:38)2024-02-01T06:38:00.149995+00:00 app[web.1]:     at SynchronousCursor.forEach (packages/mongo/mongo_driver.js:1136:22)2024-02-01T06:38:00.149995+00:00 app[web.1]:     at Cursor.<computed> [as forEach] (packages/mongo/mongo_driver.js:918:44)2024-02-01T06:38:00.149996+00:00 app[web.1]:     at OplogObserveDriver._runQuery (packages/mongo/oplog_observe_driver.js:729:16)2024-02-01T06:38:00.149996+00:00 app[web.1]:     at OplogObserveDriver._runInitialQuery (packages/mongo/oplog_observe_driver.js:658:10)2024-02-01T06:38:00.149996+00:00 app[web.1]:     at packages/mongo/oplog_observe_driver.js:191:102024-02-01T06:38:00.149996+00:00 app[web.1]:     at packages/mongo/oplog_observe_driver.js:15:92024-02-01T06:38:00.149997+00:00 app[web.1]:     at Meteor.EnvironmentVariable.EVp.withValue (packages/meteor.js:1234:12)2024-02-01T06:38:00.149997+00:00 app[web.1]:     at packages/meteor.js:550:252024-02-01T06:38:00.149997+00:00 app[web.1]:     at runWithEnvironment (packages/meteor.js:1286:24) {2024-02-01T06:38:00.149997+00:00 app[web.1]:   name: 'MongoError',2024-02-01T06:38:00.149997+00:00 app[web.1]:   [Symbol(mongoErrorContextSymbol)]: {}2024-02-01T06:38:00.149998+00:00 app[web.1]: }

So it appears that oplogs may not be working on the new server. Since the server shares the exact same codebase, we thought it must be something related to the new database. But we couldn't be sure what was wrong as we were not the one who configured the oplog in the legacy original server.

Both the old and new servers has the following environment variables configured:

OLD SERVERMONGO_OPLOG_URLmongodb+srv://user:password@oldclusterxxx.gogvv.mongodb.net/localMONGO_URLmongodb+srv://user:password@oldclusterxxx.gogvv.mongodb.net/database_nameNEW SERVERMONGO_OPLOG_URLmongodb+srv://user:password@newclusteryyy.gogvv.mongodb.net/localMONGO_URLmongodb+srv://user:password@newclusteryyy.gogvv.mongodb.net/databse_name

Also checked the networking IP address restrictions, which has no restrict so we can rule out the possibilities that the new database has IP restrictions.

So what could be the problem in the new database that causes this MongoError: no primary server available in oplog operations?

No much changes in any versions as we try not to break the legacy app:

OLD APPMongoDB 4.4.28Meteor 1.10.2mongo@1.10.0NEW APPMongoDB 5.0.24Meteor 1.10.2mongo@1.10.0