'Error while opening the virtual machine: internal error'
After upgrading to WMWare Workstation Player 16.2.0 and launching the hypervisor, the 'welcome to VMWare' splash screen came up normally. All guests were listed in the pane. On clicking any of them, however, I got an error message (stated in the Subject line). The trouble comes from the host's security features. (Host OS is Win10, version 21H1, build 19043.1319).
Here are the steps I took to resolve this error:
Click the Windows icon and type 'ransomware' in the field. The Ransomware protection app (within Windows Security) opens.
Under 'Controlled folder access', click on the link for "Allow an app through Controlled folder access". If prompted by User Account Control, allow the action.
Click the 'Add an allowed app' button at the top of the list and select 'recently blocked apps'
Click the "+" symbol for any VMWare apps...but as always, check the path to ensure you are approving the right thing!
Click the 'Close' button
Close the Windows Security window
No restart was required on my computer - I was able to immediately access the guests.