Kickstart is NOT a restoration script
Kickstart is the backup archive extraction tool. It only extracts the backup archive. It has nothing to do with the database restoration and the site reconfiguration. That is handled by the Akeeba Backup Restoration Script, the restoration script which was included in your backup archive at backup time.
This information is printed on your screen every time you run Kickstart, explained in our video tutorials, and included in several documentation pages.
You have two issues.
The first one is a backup archive extraction issue. This comes from Kickstart and it says that the backup archive is corrupt. The "unexpected error" means that your PHP on your server died without returning a response while extracting the backup archive. The only way I have seen this happen in the 20 years Akeeba Backup and its predecessor JoomlaPack have existed (and another 6 years before that I was just using PHP software and/or writing PHP software) is when there is a problem with the PHP binary on the host. In other words, this kind of hard crash does not come from the software written in PHP or the data it processes, but the PHP language interpreter itself being broken.
The second one is a database restoration issue. This comes from the restoration script which was placed in the backup archive at backup time. It says that the SQL file containing the copy of your database is corrupt. The nature of the corruption appears to be duplicated data in the SQL dump. The size of the data before that duplication, the fact that nobody else has this problem, and the fact you get hard crashes on PHP itself make me think that the root cause is that the PHP binary on your host is not working properly. I am suspecting a memory allocation issue either with PHP itself, or the zlib library it's compiled against. This class of issues would definitely cause duplicated data and hard crashes.
What I would try is first trying to use a different account on a different host. Upload the backup archive file(s) either via SFTP, or if SFTP is not possible using FTP in Binary transfer mode. Then try to extract this backup archive on that host and restore it. If the restoration does work fine on the different host then the problem is with the host you were trying to restore to when you got the issues you mention.
If, however, you still get extraction and/or database restoration issues the backup archive itself is corrupt. In this case you need to take a new backup or use a different backup archive. That said, I think that it is extremely unlikely this will be the case. This would mean that a corrupt archive somehow triggered an as yet undiscovered bug in PHP or zlib nobody else has bumped into the last 20-odd years. You see why I call it "extremely unlikely"; it's not outright impossible, but I would be shocked and incredulous if this was the case.
Nicholas K. Dionysopoulos
Lead Developer and Director
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