Thank you in advance for any tips on this.
Barely-related-background: I made a mistake on my development machine. In gparted, I chose "ignore" instead of "cancel". This is called 'choosing poorly'. Anyway, I now have freshly reinstalled my OS, apache, php, etc.
Now, as the title says, when I click "Update Asset Indexes" it gives a popup saying
getFileList() is not implemented
Any suggestions what I need to do?