Error: Specified member is not UserResolvable. - TypeError [InvalidType]: Specified member is not a UserResolvable (ThreadMemberManager.add )

[HeyItsDanny]

Which package is this bug report for?

discord.js

Issue description

Since yesterday evening the error message appears every few minutes (no specific interval recognizable):

Full error message:

[ERROR]: Error: Specified member is not UserResolvable. - TypeError [InvalidType]: Specified member is not a UserResolvable. at ThreadMemberManager.add (..../node_modules/discord.js/src/managers/ThreadMemberManager.js:99:20) at ..../node_modules/discord.js/src/client/actions/ThreadMembersUpdate.js:17:95 at Array.reduce (<anonymous>) at ThreadMembersUpdateAction.handle (..../node_modules/discord.js/src/client/actions/ThreadMembersUpdate.js:16:27) at module.exports [as THREAD_MEMBERS_UPDATE] (..../node_modules/discord.js/src/client/websocket/handlers/THREAD_MEMBERS_UPDATE.js:4:38) at WebSocketManager.handlePacket (..../node_modules/discord.js/src/client/websocket/WebSocketManager.js:355:31) at WebSocketManager.<anonymous> (..../node_modules/discord.js/src/client/websocket/WebSocketManager.js:239:12) at WebSocketManager.emit (..../node_modules/@vladfrangu/async_event_emitter/dist/index.cjs:282:31) at WebSocketShard.<anonymous> (..../node_modules/@discordjs/ws/dist/index.js:1190:51) at WebSocketShard.emit (...../node_mod

Code sample

No response

Versions

discord.js: 14.15.3

Issue priority

High (immediate attention needed)

Which partials do you have configured?

User, Channel, GuildMember, Message, Reaction, GuildScheduledEvent, ThreadMember

Which gateway intents are you subscribing to?

Guilds, GuildMembers, GuildModeration, GuildEmojisAndStickers, GuildIntegrations, GuildWebhooks, GuildInvites, GuildVoiceStates, GuildPresences, GuildMessages, GuildMessageReactions, MessageContent, GuildScheduledEvents, AutoModerationConfiguration, AutoModerationExecution, GuildMessagePolls, DirectMessagePolls

I have tested this issue on a development release

DiscordJS: 14.15.3

[JMTK]

Probably a duplicate of #10393

[didinele]

Most certainly so. If this still occurs even with #10434, feel free to re-open.

[HeyItsDanny]

Just4Info: I was told by your support team that I should open it.