Kdenlive render stuck at 100% — clear cached data, switch to MKV

✅ Issue: Kdenlive freezes or crashes right before or immediately after rendering completes at 100%.

✅ Root Cause: Encoder/driver issues, temp/cache conflicts, or MP4 final index (moov) write stalling.

✅ Solution: Clear cached data, use software (non-hardware) presets, try MKV instead of MP4, and reset configuration if needed.

Quick Start (≈1–2 min)

1. Clear cached data via Settings → Manage Cached Data (or manually under %LocalAppData%\kdenlive)
2. Switch render format from MP4 to MKV
3. Avoid 'Hardware accelerated' presets
4. Help → Reset Configuration (or check Configure Kdenlive → Environment (MLT) and restore defaults)
5. Restart Kdenlive and retry rendering

Problem Overview

When rendering videos in Kdenlive, users often report the progress bar reaching 100% but never finishing, or the application suddenly crashing. These issues typically stem from hardware encoder conflicts (NVENC/VAAPI) or temporary file access errors.

This guide covers common causes affecting both regular users and admin environments, providing the fastest resolution steps. Reports exist on some Windows/NVIDIA setups, often tied to encoder or driver behavior.

Table of Contents

• Common Causes
• Symptom Comparison Table
• Solution Steps
• Quick Q&A
• Final Checklist
• FAQ

Common Causes

• GPU-accelerated encoder crashes (NVENC, VAAPI)
• Temp folder access denied or insufficient disk space
• MP4 final index (moov) write failure causing a hang at completion

Typical Scenario

Rendering reaches 100% but the "completed" message never appears, leaving Kdenlive in a "not responding" state. This has been reported on some Windows/NVIDIA setups.

Symptom Comparison Table

Symptom	Description	Solution
Stuck at 99-100%	MP4 final index (moov) write failure	Switch output format to MKV and retry
App crashes after render	GPU accelerated encoder conflict	Avoid 'Hardware accelerated' presets
Corrupted video file	Temp folder path/space issues	Clear cached data and output to a different drive

Solution Steps

1) Clear Temporary Folders and Cache

Conflicting temp files generated during rendering can prevent Kdenlive from terminating properly. Use Settings → Manage Cached Data to clear project/all caches. If you prefer manual cleanup, delete cache, proxy, thumbs, and related job logs under the path below. Do not delete the profiles folder or kdenliverc file, as they contain your user settings.

Try this first: Close Kdenlive, then clear cached data via Settings → Manage Cached Data.

Open: C:\Users\%username%\AppData\Local\kdenlive

Kdenlive temp folder (AppData\Local\kdenlive) — example of cache/proxy/thumbnail items to clear

2) Reset Encoder Settings

If encoder options or custom presets are misconfigured, rendering may fail right before completion. Reverting to defaults and using software presets usually stabilizes completion.

• Help → Reset Configuration or Configure Kdenlive → Environment (MLT) → verify paths / Restore Defaults
• Render window → Preset list → avoid 'Hardware accelerated' → choose software presets like “Generic → MP4-H.264/AAC”

---

3) Change Output Format and Container

MP4 containers sometimes fail when writing the final index (moov). Switching to MKV bypasses this end-of-file finalization step.

• Render → Format: Change MP4 to Matroska (MKV)
• Keep audio codec as AAC
• Confirm successful completion after rendering

---

4) Use Software-Only Rendering (isolate GPU factors)

In environments where GPU encoding is unstable, software (FFmpeg CPU) rendering is more reliable. This also helps isolate encoder/driver issues.

• On Windows, try Settings → OpenGL Backend to switch backends (if available)
• On recent Windows builds, this item may not appear; keep testing with software-only render presets
• Render without using 'Hardware accelerated' presets

Exceptions and Warnings

Windows permission/path edge case

The Windows portable version doesn't typically require administrator privileges. However, if your output path is in a protected folder like Program Files, rendering may fail. Change the output to a user folder (e.g., C:\Users\YourName\Videos) or run as administrator if necessary.

Linux/AppImage: temporary location & space

If /tmp is space-constrained, set a larger temporary/cache location via Project → Project Settings → Cache Data or Configure Kdenlive → Environment → Default Folders, pointing to a disk with sufficient free space.

Quick Q&A

Video file is empty after rendering?

In some Windows setups, non-ASCII or special characters in the project/output path correlate with write failures. Test with an ASCII-only path and retry rendering.

Can I re-enable hardware encoding later?

After the issue is resolved, update your GPU drivers to the latest version before re-enabling. If the same symptoms reappear, disable it again and keep software presets.

Final Checklist

• Cached data cleared (menu or manual)
• Render format changed to MKV and tested
• 'Hardware accelerated' presets avoided
• Output path set to a local user folder
• Kdenlive exits normally after rendering

FAQ

Getting "Invalid preset" error during render?

This can occur with corrupted or custom preset values. Remove custom presets and select Restore Defaults, then re-add only known-good presets.

CPU rendering is too slow?

Before re-enabling hardware acceleration, lower output resolution to 720p to test stability/speed. If it completes successfully, the issue is likely GPU encoder-related.

Output file shows 0 bytes after render?

This can happen when the save location lacks write permission or an external drive disconnects. Change the save location to an internal drive path (e.g., C:\Videos).

References

• Kdenlive Official Documentation — FFmpeg settings and encoding guidelines.