iMovie Keeps Crashing? Here's How to Fix It on Mac and iPhone

Few things are more frustrating than losing your creative momentum because iMovie keeps crashing right in the middle of a project. Whether the app quits without warning, the timeline locks up, or an export fails at 90%, these interruptions can cost you hours of work. The good news is that most of these problems have clear causes and reliable fixes. This guide walks you through why iMovie keeps crashing, how to diagnose the issue by its symptoms, and exactly what to do to get back to editing.

Before you start fixing things, it helps to understand why iMovie is not working in the first place. iMovie is a demanding app that leans heavily on your device's processor, memory, graphics hardware, and storage. When any of those resources runs short, the app becomes unstable. Diagnosing the problem based on symptoms is the fastest way to a solution.

Here's how to read the signs:

• iMovie won't open at all. If iMovie crashes when opening or won't launch past the splash screen, the problem is usually a corrupted preference file, an outdated app version, or an incompatible macOS/iOS release. On mobile, iMovie won't open on iPhone often traces back to low storage or a background update that stalled.
• iMovie freezing or not responding mid-edit. When iMovie is freezing during editing – the spinning wheel appears, the interface stops reacting, or iMovie becomes frozen on Mac – you're typically looking at a memory shortage or an overloaded project with too many high-resolution clips and effects.
• iMovie crashing during specific actions. If iMovie crashes when importing or iMovie crashes when exporting, the trigger is almost always an unsupported media format, a damaged clip, or insufficient disk space for temporary render files.
• Random or frequent quits. When iMovie keeps crashing on Mac with no clear pattern, look at background apps eating your RAM, a full startup disk, or graphics driver issues.

If you're asking why my iMovie is not working on iPhone specifically, the culprits are narrowing to storage, an outdated iOS version, or the app itself needing an update. Understanding why my iMovie keeps crashing in your particular case makes the rest of this guide far more effective.

Most cases of iMovie not working are solved by a handful of general fixes. Work through these in order – many people find the app stops crashing after just the first two or three.

1. Update everything. Outdated software is the number one reason iMovie crashes. On Mac, open System Settings and install any pending macOS updates, then update iMovie from the App Store. On iPhone, update iOS and grab the latest iMovie version. macOS updates also bundle graphics (GPU) driver improvements, so you don't update drivers separately on a Mac – installing the system update handles it for you.

2. Restart your device. A full restart clears memory leaks and frees system resources. This alone resolves a surprising number of cases where iMovie is not responding.

3. Clear cache and render files. Old render and library files can bloat and corrupt. On Mac, open the iMovie Library in Finder (right-click it in Movies and choose Show Package Contents), then delete the Render Files folder inside your project – iMovie will rebuild it. Emptying the Trash afterward reclaims the space.

4. Free up storage. iMovie needs plenty of free space for temporary files. Aim to keep at least 10–20% of your drive empty. On iPhone, offload unused apps and delete old videos if iMovie keeps crashing on iPhone due to a full device.

5. Check GPU and performance settings. On Macs with switchable graphics, make sure the system isn't stuck on power-saving mode during heavy edits. In Battery settings, allow high-performance graphics while plugged in. This reduces stutters and helps with iMovie freezing on demanding timelines.

6. Reset iMovie preferences. If the app still misbehaves, a corrupted preferences file may be to blame. Quitting iMovie and removing its preference file (then relaunching) restores default settings and often stops iMovie crashing on launch.

7. Reduce project load. Split large projects, lower the preview quality, and disable heavy effects like the iMovie glitch effect while editing – you can re-enable them just before export. A lighter timeline means fewer crashes.

An iMovie export not working is one of the most common complaints, partly because export pushes your hardware harder than any other task. If iMovie crashes when exporting, try these targeted steps.

First, confirm you have enough free disk space – a full-length HD or 4K export can need several gigabytes of temporary space, and running out mid-render is a frequent crash trigger. Second, lower the export resolution or frame rate; dropping from 4K to 1080p, or from 60fps to 30fps, dramatically reduces the processing load. Third, export in smaller sections. If a long project fails, split it into parts, export each separately, and combine them – this isolates a single problem clip that may be corrupting the whole render.

Also check for a damaged clip. A single unsupported or partially corrupted file can halt the entire export. Remove clips one at a time (or export a copy of the project with half the timeline) to find the offender. Finally, close every other app before exporting so iMovie has full access to your CPU, GPU, and memory.

If iMovie crashes when importing footage, or iMovie keeps crashing when importing a specific file, the issue is nearly always format-related. iMovie supports a defined list of codecs, and files outside that list – certain MKV, AVI, or variable-frame-rate recordings from screen capture tools and drones – can destabilize the app.

The reliable fix is to convert incompatible files to a format iMovie handles cleanly, such as H.264 or HEVC in an MP4 or MOV container, before importing. Converting to a constant frame rate also prevents the audio-sync glitches that sometimes accompany import crashes.

Beyond format, check that the source files aren't corrupted – try playing them in another player first. Copy media from external drives to your internal drive before importing, since a slow or disconnecting external drive can cause iMovie to hang. And as always, make sure you have free storage; importing large clips onto a nearly full disk is a common reason iMovie crashes when importing on both Mac and iPhone. If you specifically face iMovie not working on iPhone during import, updating iOS and clearing space usually resolves it.