duplicate key value violates unique constraint "users_username_key"

[jwillmer]

Summary

I upgraded Mattermost to 5.34. This also required switching (upgrading) Postgres. Now this app throws the following error on startup:

2021-04-20 21:16:28.272 CEST [34] ERROR:  duplicate key value violates unique constraint "users_username_key"
2021-04-20 21:16:28.272 CEST [34] DETAIL:  Key (username)=(remindbot) already exists.
2021-04-20 21:16:28.272 CEST [34] STATEMENT:  insert into "users" ("id","createat","updateat","deleteat","username","password","authdata","authservice","email","emailverified","nickname","firstname","lastname","position","roles","allowmarketing","props","notifyprops","lastpasswordupdate","lastpictureupdate","failedattempts","locale","timezone","mfaactive","mfasecret") values ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12,$13,$14,$15,$16,$17,$18,$19,$20,$21,$22,$23,$24,$25);

Reinstalling the plugin did not help. Since it prevents the start from all other plugins I need to remove this plugin.

Steps to reproduce

Steps to reproduce the behavior:

1. Upgrade Mattermost and db via script
2. Start server

Server configuration

Operating system:

Mattermost version: mattermost-team-edition:5.34

Remind version: 0.4.4

Updated from an older Remind bot version or fresh install:
Server upgrade.

[jwillmer]

I fixed it by:

1. removing the plugin from Mattermost
2. converting the (still existing) bot user to a real user
3. deleting the user
4. reinstalling the plugin

I leave this bug open. Maybe some dev knows how to prevent this issue in the first place?