Direct answer
Green bubbles mean that conversation is using SMS/MMS/RCS instead of iMessage. The contact’s current number, iMessage registration and network state matter more than your bubble-color setting.
What this covers
- The observed symptom matches this record
- Customer-accessible settings, connections and external components
- Diagnosis before reset, deletion or component replacement
What it does not cover
- ×A model-specific error code with a different documented meaning
- ×Internal electrical, battery-cell, gas, refrigeration or sealed-component repair
- ×A guarantee that every model exposes the same control label
Capture the exact symptom
ReversibleCheck whether other iMessage conversations remain blue and whether the contact recently changed phone or number.
Run the smallest isolation test
ReversibleStart a new message to the contact’s current Apple-linked address/number and confirm both phones have data service.
Correct only the proven cause
ReversibleCorrect the saved destination or let the contact re-enable iMessage; avoid deleting history as a first step.
Verify before changing anything else
ReversibleSend a new test and confirm the input field identifies the intended service.
Evidence ledger
Sources behind this answer
Visible sources support the visible claims. Home Product Support records the publisher, the fact used and the review date; community reports can suggest an issue but do not become a published fact on their own.
Exact questions
Common follow-ups
What should I check before resetting anything?+
Check whether other iMessage conversations remain blue and whether the contact recently changed phone or number.
What is the safest isolation test?+
Start a new message to the contact’s current Apple-linked address/number and confirm both phones have data service.
When should I stop troubleshooting?+
Do not repeatedly toggle account services if Apple reports an activation issue or the contact no longer uses iMessage.
Answer for the exact device and software version shown above.