"Not sent — send a friend request first" — you can't message someone who isn't your friend or a mutual contact. Send a request with an intro note.
"Not sent — you can't message this person" — one of you blocked the other.
My message shows a clock 🕓 and isn't sent — there's no internet or Tellu is reconnecting. It will be sent automatically. If ⚠ appears, tap it to retry.
The video "isn't available" — videos stay on the server for 30 days only. Ask the sender to send it again.
I can't send a file — allowed: PDF, Word, Excel, PowerPoint, TXT, CSV, ZIP, EPUB and more, up to 100 MB. Videos up to 10 minutes.
The message wasn't translated, or was translated from the wrong language — tap the language line at the top of the chat and change the other person's language. And make sure "Translate their messages" is on in their profile.
Messages disappeared — check disappearing messages (the person's profile, and More → Privacy). If the sender deleted a message "for everyone", you see "This message was deleted".
I deleted a chat or a message by mistake — "Delete chat" and "Delete for me" are permanent on all your devices and can't be restored (the other person still sees it). Right after "Delete for me", an Undo button appears for a few seconds.
I don't see "Delete for everyone" — it appears for your own messages within 48 hours of sending only.
I don't see "Edit" — it appears for your own text messages within 15 minutes of sending, up to 5 times. "This message can no longer be edited" means the time or the number of edits ran out.
Voice typing isn't available — your phone doesn't support speech recognition, or you're in an encrypted chat.