Yeah, that error is a pain. You hit spacebar, expecting a smooth preview, and instead After Effects slaps you with 'Out of memory: 0'. You've probably already checked your RAM — maybe even added more — and it still happens. Let's cut to the chase.
The Real Fix: Clear the Disk Cache
What's actually happening here is that After Effects is choking on the disk cache, not your RAM. The number after 'Out of memory' is misleading — it's not a code that tells you which resource ran out. In most cases, it's the cache files on your drive getting corrupted or hitting a size limit. Here's the fix that works for me, every time.
- Close After Effects completely. Don't just close the project — quit the app.
- Open the cache folder. Press
Win + R, paste this, and hit Enter:
%APPDATA%\Adobe\After Effects\<your version>\You'll see folders named like Media Cache and Media Cache Files. Delete the contents of both. Don't worry — AE rebuilds them. You'll lose no actual work, just cached previews.
- Restart After Effects and try your preview again.
That alone fixes it for most people. But if you're still seeing the error, move to the next step.
Why This Works
After Effects uses the disk cache to store already-rendered frames. When you preview, it reads from that cache instead of re-rendering everything. The catch is that these cache files can get corrupted — especially if your system crashed during a previous render, or if the drive ran out of space mid-write. When AE tries to read a broken cache entry, it fails and throws that 'Out of memory: 0' error because it can't allocate the memory for the frame it expected to find. Clearing the cache forces AE to re-render from scratch, and it can't trip over a corrupted file that no longer exists.
The reason step 3 works is that AE rebuilds the cache cleanly. It's a brute-force fix, but it gets you back to work in under a minute.
Less Common Variations
If clearing the cache doesn't do it, here are a few other culprits I've seen in the wild:
1. Disk Cache Size Limit
Go to Edit → Preferences → Media & Disk Cache. Your maximum cache size might be set too high for your free disk space. AE doesn't check free space before writing; it just writes until it hits the limit, then things go sideways. Set it to 50–75% of your free space, and you're safer.
2. Corrupted Preferences File
Sometimes the cache isn't the issue — your preferences file is. It can get corrupted after a crash or a bad plugin install. Reset it by holding Ctrl + Alt + Shift while launching After Effects. It'll ask if you want to delete your prefs. Say yes. You'll have to redo your UI layout, but that beats a broken preview.
3. RAM Preview Settings
If you've set RAM preview to 'Full' resolution on a 4K comp with a dozen effects, AE might genuinely run out of memory. Lower the resolution to 'Half' or 'Third' for previews. That's not a fix for the error per se, but it prevents it from appearing when you're just scrubbing through.
Prevention for the Future
Here's what I do to keep this from biting me every other week:
- Set a disk cache limit that leaves room for your OS and other apps. On a 1TB SSD, I use 100GB — that's plenty for a few projects.
- Clear the cache regularly — at least once a week if you're a daily user. You can do it from Edit → Purge → All Memory & Disk Cache without quitting.
- Watch your drive space. If your cache drive gets below 10% free space, AE starts throwing odd errors. Keep an eye on it.
- Don't force-quit AE mid-render. If you need to stop, press Esc and let it clean up. Killing the process mid-write is a fast track to corrupted cache files.
One more thing: if you're on a laptop with a hybrid drive or an external drive, move your cache to your fastest SSD. It's not just about speed — slower drives are more prone to write errors under load, which is exactly what triggers this bug. A fast NVMe drive makes AE feel noticeably snappier, and the error becomes rare.
That's the whole deal. Clear the cache, reset prefs if needed, and keep an eye on your disk. The error is annoying, but it's never actually about how much RAM you have. Trust me, I've been through this on three different machines — it's always the cache.