If you have been plotting for some time, chances are you ran into a concerning “Failed to Open (invalid plots)” section on Plots tab from Chia Blocking UI. Before you proceed with “These plots are invalid, you might want to delete them.” direction, consider several troubleshooting steps below.
Restart Chia Blockchain
Plots can appear as Invalid if they been moved/removed from Plot Directory. This can occur if you have a process which creates .plots on one drive and then you move them to another drive. To confirm if this is the case, take a closer look for Local Harvester Plots to see if you can locate plot with the same Plot Key already on the list.
Restarting Chia Blockchain UI will remove invalid plots from the list if the error is caused by movement of plots between drives.
Chia Plots Check
To find out what else can be causing plot to appear as invalid, execute plot check command from PowerShell terminal and watch for any ERROR or WARN messages:
.\chia.exe plots check
Upgrade to Latest Chia Software
Plots created with older version of Chia software might not be compatible with newer versions of Farmer. Make sure you check for updates regularly and create new plots using most current version. On or around May 17, 2021 Chia announced support for pooling feature. Unfortunately, this change will require re-plotting of any plot that you would like to be added to pool.