After Effects can open projects created with previous versions, within limits. For example, After Effects CS5.5 and later can open and import projects from After Effects 6.5 and later.
It doesn’t go the other direction unless you use this script:
https://aescripts.com/pt_opensesame/
After Effects CS5.5 can save backward one version, to a project that can be opened by After Effects CS5. See this page:
https://blogs.adobe.com/toddkopriva/2011/04/save-project-from-after-effects-cs5-5-for-after-effects-cs5.html
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Todd Kopriva, Adobe Systems Incorporated
Technical Support for professional video software
After Effects Help & Support
Premiere Pro Help & Support
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