Major - P3 Tab completion on a secondary won't work without setting the appropriate read preference.
rs0 [direct: secondary]> db.slaTab completion error: MongoError: not master and slaveOk=false at MessageStream.messageHandler (/home/alex/Workspace/mongo/mongosh:46582:20) at MessageStream.emit (events.js:315:20) at MessageStream.EventEmitter.emit (domain.js:486:12) at processIncomingData (/home/alex/Workspace/mongo/mongosh:43478:12) at MessageStream._write (/home/alex/Workspace/mongo/mongosh:43374:5) at writeOrBuffer (_stream_writable.js:352:12) at MessageStream.Writable.write (_stream_writable.js:303:10) at Socket.ondata (_stream_readable.js:719:22) at Socket.emit (events.js:315:20) at Socket.EventEmitter.emit (domain.js:486:12) { topologyVersion: { processId: ObjectId("601c0d6951aabc0c661dc8d2"), counter: 4 }, ok: 0, code: 13435, codeName: 'NotPrimaryNoSecondaryOk', '$clusterTime': { clusterTime: Timestamp(1, 1612451538), signature: { hash: Binary(Buffer.from("0000000000000000000000000000000000000000", "hex"), 0), keyId: 0 } }, operationTime: Timestamp(1, 1612451538)
However SERVER-49990 removes `setSlaveOk` which users are used to and the MongoError still alludes to.
rs0 [direct: secondary]> db.getMongo().setSlaveOk(true)
MongoshDeprecatedError: [COMMON-10003] setSlaveOk is deprecated.
Trying to set slaveOk does not point users to anything relevant. If you discover the alias (SERVER-49990) and try this the error is a little more helpful at least:
rs0 [direct: secondary]> db.getMongo().setSecondaryOk(true)
MongoshDeprecatedError: [COMMON-10003] Setting secondaryOk is deprecated, use setReadPref instead
Making the setSlaveOk and setSecondaryOk errors the same would at least make this a little easier for users to action. Adding documentation links to the errors would be even better 