The road lights along state-owned highways are owned by the state or the municipality. You can report the issue to the Centre for Traffic Customer Service using the feedback channel. The feedback is forwarded either to the lighting contractor or the municipality.
Generally, individual light bulbs are not changed separately, but only in connection with regular check-up rounds.
If a road section is completely dark, you can notify the Road User Line at 0200 2100 (24 hours a day). They will forward your message to the contractor, who will take measures according to the quality requirements set by the Finnish Transport Agency. The contract manager will also be notified.