I am using the Tencoder portable app, (installed on a thumb drive) and got the following message while trying a dvd rip
Assertion v>0 && v
New: Audacious (June 1, 2023), Platform 25.0 (Apr 07, 2023)
New Apr 14: macOS Portable Drive Support
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TEncoder has not received any updates for 3 years, so you may be running into a DRM issue, I ran into a different DRM-related issue when I attempted a DVD rip to confirm your problem.
Please try using the installed version, to ensure the problem is not with TEncoder itself.