Followed these instructions verbatim and ended up exactly where I was before.
Process: After Effects 
Path: /Applications/Adobe After Effects CC/Adobe After Effects CC.app/Contents/MacOS/After Effects
Version: 12.0 (12.0)
Code Type: X86-64 (Native)
Parent Process: launchd 
Responsible: After Effects 
User ID: 1115053041
Date/Time: 2014-04-22 12:35:21.115 -0700
OS Version: Mac OS X 10.9.2 (13C64)
Report Version: 11
Anonymous UUID: E0811F87-6ECC-6EB8-414F-5D27B9C93261
Crashed Thread: 0 Dispatch queue: com.apple.main-thread
Exception Type: EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: KERN_INVALID_ADDRESS at 0x000000000000000f
VM Regions Near 0xf:
__TEXT 0000000100000000-0000000100004000 [ 16K] r-x/rwx SM=COW /Applications/Adobe After Effects CC/Adobe After Effects CC.app/Contents/MacOS/After Effects
Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0 libc++abi.dylib 0x00007fff94b8a774 __cxxabiv1::__si_class_type_info::has_unambiguous_public_base(__cxxabiv1::__dynamic_cast_ info*, void*, int) const + 0
1 liboptix.1.dylib 0x000000010f812017 __dynamic_cast + 119
2 COR.dylib 0x00000001017db0b3 CORp_InitBIB(bool) + 1075
3 com.adobe.AfterEffectsLib.framework 0x000000010031c61f unsigned int U_RegisterExceptionTranslator<bool (*)(std::exception*, int*)>(bool (*)(std::exception*, int*)) + 351
4 U.dylib 0x0000000102e36491 U_TranslateAndReportException(std::exception&) + 273
5 FILE.dylib 0x000000010186fc38 FILE_Create + 472
6 com.adobe.AfterEffectsLib.framework 0x0000000100233881 CEggApp::GetWorkspaceDirs(std::basic_string<unsigned short, std::char_traits<unsigned short>, dvacore::utility::SmallBlockAllocator::STLAllocator<unsigned short> >&, std::basic_string<unsigned short, std::char_traits<unsigned short>, dvacore::utility::SmallBlockAllocator::STLAllocator<unsigned short> >&, std::basic_string<unsigned short, std::char_traits<unsigned short>, dvacore::utility::SmallBlockAllocator::STLAllocator<unsigned short> >&) const + 545
7 com.adobe.AfterEffectsLib.framework 0x000000010025f6cd CEggApp::BirthWorkspaceMgr() + 77
8 com.adobe.AfterEffectsLib.framework 0x00000001002652ad CEggApp::IEggApp(bool, bool) + 861
9 com.adobe.AfterEffectsLib.framework 0x000000010024cca2 CEggApp::CEggApp(bool, bool, int) + 1154
10 com.adobe.AfterEffectsLib.framework 0x00000001002735ec MainMain(bool, bool, bool, bool, bool, bool, unsigned short const*, bool, void**, int, int, int) + 1052
11 com.adobe.AfterEffectsLib.framework 0x000000010027319b EggMain(bool, bool, bool, bool, bool, bool, unsigned short const*, bool, int) + 59
12 com.adobe.AfterEffects 0x00000001000039b7 main + 1927
13 com.adobe.AfterEffects 0x0000000100003224 start + 52
The crash is because you're trying to use After Effects CC (12.0), not a version after that. You need an update to run After Effects on Mac OS X v10.9 (Mavericks):
If you can't install the updates, then contact Adobe Technical Support:
Please read above. I have tried multiple times to install the update and run into the same problem over and over that everyone else is running into in multiple threads.
Also, I have tried to contact customer service and they seem more lost than I am:
I contact Adobe Customer Support. I end up in a screen share with some Adobe representative with his previous customers computer screen still open in the screen share program, basically showing me everything on her computer... and the agent sits there pretty much helpless blaming her for 15 minutes. Clearly helpful. (breach of security?)
I have literally tried every avenue of troubleshooting to resolve this and it's beginning to seem hopeless.
Do you have any other solutions or is this product just dead in the water for me?
I just asked someone on our technical support staff to contact you. They said that they got your voicemail. They'll keep trying.
Note that our first-tier customer support staff are not the same as our video products' technical support staff.
I'm having the exact same problem. Is there a solution for it?
Todd — I'm having this exact same problem. Tier 1 support via chat in India is hopelessly ineffective.
The big question on my mind is after using CC Cleaner to de-install Adobe CC, why doesn't CC Desktop install the most current versions of the CC apps? AE is at 12.2.1, yet CC Desktop installs 12.0 which won't work on Mavericks.
> Tier 1 support via chat in India is hopelessly ineffective.
Then insist on being escalated to a higher tier.
> why doesn't CC Desktop install the most current versions of the CC apps? AE is at 12.2.1, yet CC Desktop installs 12.0 which won't work on Mavericks.
The base x.0 version is installed and then the updates are immediately applied. If something is preventing the update, that is where problems arise.
It looks like this error might be related to Creative Cloud Packager — my initial Photoshop CC install was done with it. It looks like the CC Cleaner app leaves something behind that prohibits updates from being applied even after a deinstall and then reinstall with CC Desktop.
I'm reinstalling with CC Packager now, but I've enabled updates for admin users.
Found this thread before found thread with solution that worked for me; so for people in similar situation as me:
Answer in following thread (at least for me): adobe application manager fails to update
I found the problem is due to AAME installing a pref file which DISABLES updates from working in CS products. The AdobeUpdaterAdminPrefs.dat file. This is quite a pain and
someone installing Adobe CS with AAME may not be aware that this file is being installed, making it very confusing for administrators.
The solution is to delete or rename the <Startup Disk>/Library/Application Support/Adobe/AAMUpdaterInventory/1.0/AdobeUpdaterAdminPrefs.dat
Then run Update from Photoshop (or other app probably) and Update works.
Full details are on Adobe's website at http://helpx.adobe.com/creative-suite/kb/disable-auto-updates-application-manager.html"
Should add, file is located here in Windows:
"C:\Program Files (x86)\Common Files\Adobe\AAMUpdaterInventory\1.0\AdobeUpdaterAdminPrefs.dat"
Should also add that the file is created on first install and is useful - replace when update completed or modify line:
NB: You will need admin rights for this.