I am running WorkStation Pro 15 on Windows 10 Pro 64bit and for all of my virtual machines I am now getting the error message when powering on any of my virtual machines of:
Cannot connect the virtual device floppy0 because no corresponding device is available on the host.
At one time the USB floppy disk A: was recognized but now it is not recognized anymore by the floppy drive under Auto Detect.
I have found that I need to disable auto-detect, and manually specify the drive letter for the floppy on my VMs. Hand-edit the vmx file, change floppy0.AutoDetect = "false", and Device = "A:" or whatever your USB drive letter maps to.