Nobody can tell you anything without exact system info or other technical details like what's used in your comp, comp settings, disk cache settings etc..
Please give us the information Mylenium mentions so we can help you.
What, exact, version number of AE are you using?
Still having preview issues? Let us know so that we can assist you.
Hello! I resolved the problem with After Effects, but now I'm having the same exact problem with Adobe Media Encoder CC 2017. I read that with this error you have to "rename the file" but I'm not sure which file I'm supposed to rename and when I try to find the files from the error summary (as shown in the pictures attached) the file doesn't exist on my computer.
I would suggest creating a post about your Adobe Media Encoder issue over in Adobe Media Encoder (AME)
Please provide them more information such as what operating system you are using, what you are doing when you run into the problem with AME, and what your settings are in AME.
Any chance you can mention how you got the AE green bar back?