Chat issues

• Why chat history is different between the smartphone version of LINE and LINE for PC
• I can't send/receive messages
• I received a chat message saying "Start chatting with your new friend now!"
• I suddenly became unable to use a feature
• I suddenly became unable to send chat messages on LINE
• I can't send/receive/open photos/videos/voice messages
• Chat list information is incorrect
• Issues with backing up or restoring your chat history
• I entered the wrong backup PIN on my new device
• My chat history disappeared
• Clearing cached data to make LINE run faster