my ninja dualbrew pro coffee maker is showing "CLn" on the display and won't brew, what does that mean?

The "CLn" message indicates heavy calcium scale buildup in the heater for the mode you are trying to use. The brewer has stopped to prevent damage and requires an immediate clean/descaling cycle.

FIX:

1. Place the empty carafe under the brew basket.
2. Fill the water reservoir to the Travel Mug line (16 oz) with white vinegar. Fill the rest with water up to, but not exceeding, the Full line. Only use white vinegar.
3. Press the CLEAN button, then press the START BREW button to begin the cycle.
4. The cycle takes about 75 minutes. Do not remove the carafe during the cycle.
5. When it finishes, it will beep and display "End". Empty the carafe and clean it thoroughly.
6. Run a water-only flush cycle on the same mode to clear any vinegar taste. Discard that water.

IF THAT DIDN'T WORK: If the "CLn" message returns quickly, you likely have hard water. You may need to run a second clean cycle on the same mode to remove additional buildup. For future prevention, run the clean cycle whenever the orange Intelligent Clean Cycle Indicator illuminates.

HEADS UP: Hard water causes scale faster. If you ignore the orange indicator, the brewer will eventually stop and display "CLn". Never cancel a clean cycle mid-process—if you do, the brewer will not be descaled properly and you will need to start the full cleaning process over.