Hi there! I see you're encountering Error 4001 with the KOCOWA app on your Mac running OS X 10.15.7. Just to get a clearer picture: when exactly do you see this error? Is it during sign-in, while trying to watch content, or somewhere else in the app?

Meanwhile, to start troubleshooting this error 4001, here are some steps you can try:

1. Restart your Mac and Wi-Fi router: This refreshes your device and network connection which often resolves temporary glitches.

2. Update your KOCOWA app and browser: Ensure the app and any browser you use for KOCOWA are up to date with the latest software versions available for OS X 10.15.7.

3. Clear app cache and data: Since macOS doesn’t have a direct app cache clearing option like mobile, try deleting and reinstalling the KOCOWA app. This removes corrupted data that might cause the error.

4. Check your internet connection: Make sure your Wi-Fi is stable and fast enough for streaming.

5. Try using KOCOWA in a different browser: Sometimes browser-specific issues trigger errors. Safari or Chrome could behave differently.

If you’ve already tried any of these, let me know which ones, and we can dig deeper. Also, if you could share the exact error message text or when it occurs, that would help me suggest more targeted fixes.

Looking forward to your reply!