I do not have or had a7 ,so I do not know how it was different .

but in my a8 manual , under troubleshooting -- error messages , the error code you recieved is :

Error E355: Startup failure
The engine won't start this published project because the published project folder (.CD) contains wrong content - for instance, when a file was deleted or modified after publishing. Make sure that the project starts fine in development mode, that you have no duplicate files in your project folders and that the .CD folder contains the original content that was generated by the publish process. Also look for error messages during the publish process that indicate missing files.

other than that I dont really see anything wrong (not knowing a7)