It's not an error. That's the startup sequence for the Air Quality Indicator.
During the first 30 seconds after powering up, the indicator will cycle through blue, amber, and red. This is normal. After about 4 minutes, the Smart Sensor will finish detecting the air quality and the light will settle on a color representing current conditions.
If that didn't work: If the lights continue flashing in an unusual pattern or the unit doesn't start, unplug it. Check that all filters are correctly installed. Running the unit without filters can damage it.
Heads up: In Sleep Mode, the Air Quality Indicator light is disabled to avoid disturbance.