Start with common troubleshooting steps:
- Check known issues that may cause Premiere Pro export failures.
- Update Premiere Pro.
- Restart Premiere Pro.
- Restart your computer to resolve system issues.
- Check the System Compatibility Report for info on GPU drivers.
- Remove any punctuation marks in the media, the project file, or the output name.
- Make sure you have enough free disk space on the machine. .mp4 files need much more space than the output file to process.
- Export to a different hard drive on your computer. Do not save directly to Drop Box or similar file synching service.