www.makemkv.com

I know this thread is over five years old, but the fact I only stumbled on it yesterday while researching the exact same problem hopefully means what I've discovered will be of use to others in future. First, you need to take a backup of the Blu-ray disc in MakeMKV to extract all the required files....

Thank you Mark - no more trying to 'jump start' MakeMKV every time I open it in future...

You're not alone. I have exactly the same problem, albeit in Windows 11 - started at some point in the last week. I tried rolling back my system a week (Macrium Reflect) to when it was definitely working, but got the same error. Removed Malwarebytes - no dice. No mention of Bitdefender blocking it i...