MongoServerError: WriteConflict error on MongoDB Atlas

[tyteen4a03]

Link to reproduction

No response

Describe the Bug

When using MongoDB Atlas, sometimes writes fail with "WriteConflict" error.

To Reproduce

See: https://discord.com/channels/967097582721572934/1182227009603117116/1182227009603117116

Payload Version

2.5.0

Adapters and Plugins

No response

[tyteen4a03]

Note: I get this issue most frequently when I am doing a lot of writes at the same time.

[PrimarchAlpharius]

I had the same problem doing an update in the afterLogin hook.
It was persistently throwing a WriteConflict, even though it was the only place I was explicity writing to the database.

Not running Atlas, but a self-hosted replica set.
Considering I had no issues in my development environment, I found in the docs that Payload switches to Mongo Transactions by default when connected to a replica set.

After disabling transactions in payload.config.ts with transactionOptions: false everything started working fine.

[DanRibbens]

@PrimarchAlpharius Can you confirm that the latest update to the db-mongodb adapter fixes your issue if you reenable transactions?

[PrimarchAlpharius]

@DanRibbens Confirming it works, thanks!

[DanRibbens]

Note: I get this issue most frequently when I am doing a lot of writes at the same time.

@tyteen4a03 Are you still running into this on the latest version of Payload and db-mongodb?

If you are using hooks that use the Payload local API, make sure you pass the req through to any payload local API calls so that the transaction is used. If you call the database models directly, you can also pass the session in the options as: payload.db.collections[slug].findOneAndUpdate(query, data, { session: payload.db.sessions?.[req.transactionID] } })

I hope this helps! I'm closing this issue, but I will re-open if somebody can provide steps for reproduction and tag me so I see it.

[BrianJM]

Mark suggested disabling transactions in discord.

Could be related to #4350.