PROBLEM
I can't launch Capture One as I get this error "Another instance of capture one is already running". How can I fix that?
SOLUTION
When you get the following error "Another instance of capture one is already running" while trying to launch Capture One, it means that some software process is still running in the background.
This warning may also appear when you have 2 or more Capture One versions installed on the same computer (which is not recommended) and try to open another version while another is still running.
Mac
Right-click on the Capture One icon in the dock panel and select Force Quit from the context menu to stop the processes that are still running in the background. Reboot your computer and launch Capture One.
Windows
Press Ctrl+Shift+Esc to open the Task Manager. Take a look through the list in the Processes tab to define whether there are any processes related to Capture One that are still running in the background. If so, click End Process to stop those. Reboot your computer and launch Capture One.