Unable to allocate memory | After Effects

Try to reduce the amount of memory allocated to other applications:

1. On Windows, select Edit > Preferences > Memory & Performance.
   On macOS, select After Effects > Preferences > Memory & Performance.

Change the RAM reserved for other applications and click OK.

Purge Memory and Disk Cache:

1. On windows, select Edit > Purge > All Memory & Disk Cache.
   On macOS, select After Effects > Edit > Purge > All Memory & Disk Cache.
   
2. To delete all the files from your disk cache, click OK.
   

Another way to clean Media and Disk cache is:

1. On Windows, select Edit > Preferences > Media & Disk Cache.
   On macOS, select After Effects > Preferences > Media & Disk Cache.
2. In the Disk Cache dialog, click Empty Disk Cache to clean disk cache and click Clean Database & Cache to clean media cache. 
   

If Mercury Transmit is enabled, disable it. 
On Windows, go to Edit > Preferences > Video Preview and uncheck Enable Mercury Transmit.

On macOS, go to After Effects > Preferences > Video Preview and uncheck Enable Mercury Transmit. 

Remove any third-party plugins. 

macOS location

/library/application support/adobe/common/

Windows location

C:\Program Files\Adobe\Common\Plug-ins

C:\Program Files\Adobe\Adobe Media Encoder CC 2017\Support Files (for external plugins)

Create a pre-comp of the existing composition. To create a pre-comp, select all the tracks in the timeline and right click. From the drop-down menu, select Pre-compose.

Reset preferences for After Effects. Ensure After Effects is closed in your machine (while following the steps).

macOS

1. Go to your desktop and click GO on the Menu bar.
   
2. Select Go to Folder from the drop-down and type the following path: /library/preferences/adobe
   
3. From the list of applications, select After Effects and rename it as ’After Effects1’.
   
4. Go to Documents folder in your computer and open the folder named Adobe.
   
5. In the Adobe folder, rename the After Effects folder as ’After Effects1’.
   

Windows

1. In the Run command (Win key+R) dialog, type %appdata%.
2. Open the folder named Adobe.
3. Rename the After Effects folder as 'After Effects1'.
4. Close the window and open Documents folder.
5. In the Adobe folder, rename the After Effects folder as 'After Effects1'.

Check the composition creating issue:

1. Create a blank project.
2. Turn on Caps Lock and try to import the faulty project.
   
3. Open compositions one by one and toggle Caps Lock to check which composition is creating issue.
   

Ensure that the Illustrator files are offline or try to convert the Illustrator files to Shape layers.

If you have used multiple display cards, disable one of them.

If you have applied any expressions, convert them to keyframes.

Try to open the project in After Effects.

Disconnect any extra monitor attached.