After Effects 'Unable to allocate 0.000 MB of memory' — Fixed

If After Effects is throwing Unable to allocate 0.000 MB of memory at you, take a breath. The number is nonsense — 0.000 MB is a lie. AE isn't actually asking for zero megabytes. What's happening is that it tried to allocate a block, the request failed, and the internal logging rounded the failed size to zero on the way out the door. The real problem is upstream: a full scratch disk, a corrupted media cache database, or a busted preferences file.

I've seen this exact error on Windows 10 and 11 boxes running AE 2021 through 2024, and on macOS Monterey through Sonoma. It's rarely the RAM. It's almost always the cache.

Work through this in order. Stop when it's fixed.

Step 1: The 30-second fix — Purge everything

AE hoards memory like a squirrel. Purging is free and fixes the error maybe 30% of the time. Do this first because it costs you nothing.

1. Save your project. Actually save it, don't just Ctrl+S and hope.
2. Go to Edit > Purge > All Memory & Disk Cache (Windows) or After Effects > Purge > All Memory & Disk Cache (macOS).
3. Wait for the purge to finish. On a big project this can take 10–30 seconds.
4. Try your render or preview again.

If it works, great. But it'll probably come back the next time you load a heavy comp. That tells you it's a disk or cache problem, not a transient glitch. Move on.

Also — check your RAM allocation while you're here. Edit > Preferences > Memory & Performance. If you've got 32 GB total and left only 2 GB for other apps, AE is starving the OS and the OS is fighting back. Leave at least 6–8 GB for the system on a 32 GB machine, and 8–12 GB on a 64 GB machine. On 16 GB systems — honestly, cap AE at 10 GB and accept that you need more RAM for 4K comps.

Step 2: The 5-minute fix — Reset preferences

Preferences files corrupt. It happens after a crash, after a Windows update, after you install a plugin that fights with another plugin. Corruption in the pref file can cause AE to miscalculate available memory and blow up during allocation.

Back up first. On Windows the prefs live at:

%APPDATA%\Adobe\After Effects\[version]\Adobe After Effects [version] Prefs.txt

On macOS:

~/Library/Preferences/Adobe/After Effects/[version]/Adobe After Effects [version] Prefs.txt

Rename that file (or just move it to your desktop) and relaunch AE. It'll build a fresh prefs file. Note that this wipes your workspace layout, recent projects, and any custom keyboard shortcuts. That's the tradeoff.

If AE starts fine after this, you've found the culprit. If the error comes back the moment you open the same project, the prefs weren't the issue — the project's cache references are. Go to Step 3.

Step 3: The 15-minute fix — Nuke the Media Cache

This is the one that actually fixes the Unable to allocate 0.000 MB of memory error most of the time. The Media Cache Database (MCDB) holds indexed data for every clip AE has ever touched. When it gets corrupted — and it does, especially if you've had a hard crash or your cache drive has been near full — AE tries to read garbage, fails the allocation, and logs this error.

Close After Effects completely. Not minimized. Quit.

Then find the Media Cache folder. Default location on Windows:

%APPDATA%\Adobe\Common\Media Cache Files
%APPDATA%\Adobe\Common\Media Cache

On macOS:

~/Library/Application Support/Adobe/Common/Media Cache Files
~/Library/Application Support/Adobe/Common/Media Cache

Delete the contents of both folders. Don't delete the folders themselves unless you want to recreate them manually. The first time you relaunch AE after this, it'll rebuild the cache and every clip will re-index. On a big project that can take 10–20 minutes of import time. That's normal.

Check the disk cache location too

While you're in the weeds: Edit > Preferences > Media & Disk Cache. Look at the Disk Cache Location. If it's pointing at your system drive (C: on Windows, Macintosh HD on macOS) and that drive is over 90% full, you've found your problem. AE refuses to allocate cache space when the target disk is nearly full — and reports it as a memory error, which is infuriating.

Set the disk cache to a dedicated SSD with at least 200 GB free. Don't use external USB hard drives. Don't use network drives. Don't use a spinning disk if you can avoid it. When the cache location itself is full, AE can't even write the error log properly, which is why you get the 0.000 MB nonsense.

If you're on a laptop with only one drive and it's full — move your project files, renders, and footage to an external drive. Get C: under 80% and try again.

When none of that works

A few less common causes worth checking if you've done all three steps and it still fails:

• Bad plugin. Third-party plugins (Trapcode, Element 3D, particular offenders) can corrupt memory requests. Disable them by moving the plugin folder temporarily and see if AE renders cleanly.
• Corrupted project file. Try importing your project into a fresh AE project via File > Import > After Effects Project. If it loads from there, the original project's metadata was damaged.
• Outdated GPU driver. Adobe's Mercury Playback Engine relies on CUDA or Metal. A driver mismatch after a Windows update is a known trigger. Update to the latest Studio driver if you're on NVIDIA.
• Windows page file disabled. Some sysadmins disable the page file for "performance." AE needs it. Set it to system-managed. This one bites people who followed a 2012 tuning guide and never revisited it.

The 0.000 MB figure is a red herring. Stop chasing RAM upgrades. The allocation failure is a symptom of a cache or disk issue 90% of the time.

Quick reference

If you've cleared the cache, reset prefs, moved the scratch disk, and it's still failing — you're looking at either a hardware RAM issue (run MemTest86 overnight) or a project file that's fundamentally broken. At that point, reconstruct the comp in a fresh project. It's faster than fighting it.