Inquiry regarding unexpected library conversion prompt (ver. 6.8.6)

I am suddenly being prompted to perform a library conversion. Although the software was functioning normally until yesterday, I received the following message upon startup today: "To use a library used in ver. 5 or earlier in ver. 6, conversion is required."

I am concerned about the potential loss of my existing library data. Could you please clarify the cause of this message and provide a solution to resolve it safely?

Software Version: rekordbox ver. 6.8.6