Rather than dig myself I thought I'd ask for a new suggestion. I'm not sure whether my windows installation is there or not. I could use a 3rd party installer but that might make my situation worse. When I tried to put the file back from my desktop with drag and drop or copy/paste into the Finder directory, it refused. So tried to put the Windows 7 (64 bit).vdi file back from the trash and put back wasn't an option. When I went to uninstall VirtualBox 7, the uninstall refused and I got this error message: “VirtualBox_Uninstall.tool” can’t be opened because Apple cannot check it for malicious software. Here we will download macos-guest-virtualbox.sh using Wget as below. We will proceed and install macOS Catalina on VirtualBox using the push-button installer. Expecting I could copy it back if something went wrong. Step 2: Download and Install macOS on Virtualbox. This update also includes bug fixes and other improvements. The update also improves the stability, reliability, and security of your Mac.

I thought it would be safe to make a back up, I copied the Windows 7 (64 bit).vdi to my desktop and then deleted it in the folder where I copied it from. macOS Catalina 10.15.4 introduces iCloud Drive folder sharing, Screen Time communications limits, Apple Music time-synced lyrics view, and more. Skipping the convoluted explanation of why I did this.

Your VMs should be unaffected - you are changing the software, not purging your data.

Mac os 10.15 vbox