Black frames flashes when I export a video

Hi @joang53391000,

Thanks for the notes. Sounds very frustrating. Are any effects applied to the clips where you see the black frames? If so, please try updating to 24.2 if you have not already done so. Does that help? Let us know. Sorry for the problem.

Regards,
Kevin

by any chance was your clip shot on a smart phone or with a screen recording program?  If so, it's because your source has a variable frame rate.  

https://community.adobe.com/t5/premiere-pro/faq-issues-with-screen-recorded-footage-in-premiere-pro/td-p/10874355?page=1

Try resetting the preferences:
https://community.adobe.com/t5/Premiere-Pro/FAQ-How-to-reset-trash-preferences-in-Premiere-Pro/td-p/...

If that doesn't work, try resetting the Workspaces:
Reset a workspace
Reset the current workspace to return to its original, saved layout of panels.
1. Do one of the following:
• Click the Workspace menu icon and select Reset to Saved Layout.
• Choose Window > Workspace > Reset to Saved Layout.
from here:
https://helpx.adobe.com/premiere-pro/using/workspaces.html

If that doesn’t work, try updating or rolling back your graphics driver directly from the video card manufacturer’s site.

What kind of media are you working with?

Can you try to clear your media cache and previews?

How about you render & replace the video clip that's giving you the problem?