Premiere Pro Export Error 39 (Muxer Failure) — Fix “stuck at 99%” with Software Encoding & Drive Space

Last updated: September 28, 2025 | Reading time: ~5 minutes

Quick Fix Summary

Premiere Pro Export Error 39 is typically caused by insufficient storage space or hardware encoding issues. Check these items in order:

1. Ensure ample free space on both the export destination and the system drive
2. Delete all media cache and restart the program
3. Switch hardware encoding to Software Encoding
4. Update GPU drivers to the latest version

Export > Video > Encoding Settings > Performance: Switch to Software Encoding | Source: Adobe Official Documentation

Table of Contents

1. What is Export Error 39?
2. 4 Immediate Solutions to Try
3. Detailed Solutions by Cause
4. Prevention Tips
5. Frequently Asked Questions
6. Summary & Additional Resources

What is Premiere Pro Export Error 39?

Error 39 is an 'Error compiling movie' error that occurs when exporting video in Adobe Premiere Pro. It typically appears when there's a Muxer Failure—a failure in the process of combining encoded video and audio data into the final file container.

Common symptoms:

• Export suddenly stops at 80-99% progress
• Displays "Error compiling movie. Unknown error." message
• Repeatedly fails at the same point
• Only occurs with certain formats (H.264, HEVC)

4 Immediate Solutions to Try

Most Error 39 issues can be resolved with the methods below. Try them in order:

1. Free Up Storage Space

This is the most common cause. Check both your export destination drive and system drive.

• Free space: Ensure ample headroom on both the export and system drives. Large projects can require significant temporary space during encoding/muxing.
• Check locations: Export destination folder + C: drive (Windows) or startup disk (Mac)
• Quick fix: Delete unnecessary files or change export location to another drive

2. Completely Delete Media Cache

Corrupted cache files may be the culprit. Cache files are safe to delete and will regenerate automatically when needed.

1. Go to Edit → Preferences → Media Cache
2. Click Delete button → Select Delete all media cache files
3. Completely quit Premiere Pro and restart
4. Reopen project and retry export

3. Switch to Software Encoding

This bypasses GPU hardware encoding issues. Particularly effective with H.264/HEVC formats.

1. (Classic UI) File → Export → Media → Video tab
2. (New UI) Export workspace → Right panel Video → Encoding Settings
3. Change Performance from Hardware Encoding → Software Encoding
4. Retry export (takes longer but more stable)

4. Update GPU Drivers

Outdated drivers can cause hardware encoding errors.

• NVIDIA: Use GeForce Experience or download latest Studio Driver from official site
• AMD: Update through AMD Software or official site
• Intel: Use Intel Graphics Command Center or official site

Detailed Solutions by Cause

Storage Space Issues (Common)

Situation-specific solutions:

• Internal SSD full → Export to external drive or clean up unnecessary files
• External drive issues → Verify USB 3.0+ connection, temporarily switch to internal drive
• Network drive errors → Export to local drive first, then move

Additional checkpoints:

1. Clear preview files: Delete Preview folder within project directory
2. Clear auto-save files: Remove old files from Adobe auto-save folder
3. Clear system temp files: Use Windows Disk Cleanup or Mac Storage Management

File System Check (External Drives)

FAT32 has a single-file size limit of ~4GB. For large exports, use exFAT/NTFS (Windows) or APFS/exFAT (macOS) to avoid “disk full/invalid output” errors.

Hardware Encoding Issues (Common)

Even the latest GPUs can fail hardware encoding under certain conditions.

Hardware encoding failure conditions:

• 4K+ ultra-high resolution videos
• Complex effects or multiple layers
• Insufficient GPU memory (VRAM)
• Outdated or unstable drivers

Systematic solution approach:

1. Check System Compatibility Report
   • Run Help → System Compatibility Report
   • Follow recommendations if warnings appear
2. Test with alternative formats
   • Try ProRes 422 or DNxHR instead of H.264
   • If successful, re-encode to H.264 separately
3. Temporarily lower resolution
   • Test export at 4K → 1080p
   • If successful, gradually increase resolution
4. Try a built-in export preset instead of a custom preset to rule out preset corruption
5. Remove special characters from media/project/output file names and folder paths (e.g., ?, /, \, :, *, “, <, >)

If You're Exporting H.264/HEVC, Also Test This

1. Go to Edit → Preferences → Media.
2. Uncheck Enable hardware accelerated decoding (restart required).
3. Restart Premiere Pro and try the export again.

Project/Cache Corruption (Rare)

Rarely, project files or cache become corrupted, causing repeated failures at specific points.

1. Verify project integrity
   • Split sequence before and after problem area
   • Test each part separately for export
2. Reset preferences
   • Hold Alt+Shift (Mac: Option+Shift) while launching Premiere Pro
   • Confirm in Reset Preferences dialog
3. Use Adobe Media Encoder
   • Add to AME queue instead of direct Premiere export
   • Try encoding in AME with identical settings

Error 39 Prevention Tips

Regular maintenance checklist:

1. Weekly: Clear media cache (Edit → Preferences → Media Cache → Delete)
2. Monthly: Check for GPU driver updates
3. Before projects: Ensure sufficient free storage space on working and export drives
4. Large projects: Export to intermediate codec (ProRes, DNxHR) first

Export Best Practices

• Test exports: Verify settings with 10-30 second clips before full export
• Segment approach: Break long videos into multiple parts for export
• Preset backup: Save successful Export Presets for reuse
• Hardware monitoring: Check GPU temperature and usage (MSI Afterburner, etc.)

Frequently Asked Questions

Q1. Is there a quality difference between hardware vs software encoding?

At identical bitrate settings, quality differences may be small in many cases. Hardware encoding is faster, while software encoding can be more stable and sometimes yields better results with complex content. Test a short clip with both and choose the more reliable output.

Q2. Is it safe to export directly to an external drive?

While possible with USB 3.0+, connection stability and bandwidth issues can cause failures. For important exports, it's recommended to export to internal SSD first, then move the finished file to external storage.

Q3. Is it safe to delete media cache?

Yes. Cache consists of temporary files for playback performance improvement. After deletion, they'll regenerate automatically when needed. Regular cache clearing benefits system performance.

Q4. What if Error 39 keeps occurring?

If the above methods don't resolve the issue, try:

• Test the same project on a different computer
• Try exporting through Adobe Media Encoder
• Export to intermediate codec (ProRes, DNxHR) first, then re-encode
• Address System Compatibility Report warnings and reinstall drivers

Q5. How can I reduce export time?

Time-saving methods:

• Use hardware encoding (when error-free)
• Edit with proxy media, export with originals
• Pre-render unnecessary effects
• Use SSD storage and ensure sufficient RAM

Summary & Additional Resources

While Premiere Pro Export Error 39 may seem complex, it's usually a storage space or hardware encoding settings issue. Following this guide's solutions in order should resolve most cases.

Key Takeaways

1. Storage space: Ensure ample free space on export and system drives
2. Cache management: Regularly delete media cache
3. Encoding settings: Switch to Software Encoding when issues arise
4. Drivers: Keep GPU drivers up to date

Additional Learning Resources

• Resolve Premiere Pro project export errors — Adobe Official Guide
• Automatically manage your media cache files — Adobe Official Guide

Was this guide helpful? Check out our other Premiere Pro troubleshooting guides!

↑ Back to Top