There are two ways to send the backup archive to the remote server. One is via FTP/SFTP, the other is using Kickstart.
The second method does POST requests with 1MB of raw file data to the Kickstart file we uploaded to the remote server.
If the host is intercepting the POST request and removing its data you get the problem you see.
The root cause is in the host's server protection. Backup archives are not the typical simple POST request with a couple of predefined parameters. We are posting raw binary data. This kind of data is very likely to be considered problematic by an overly paranoid server protection configuration since it cannot reasonably be inspected.
We REALLY DO KNOW what the problem is and our advice as people who have done this troubleshooting and engaged with clients who tried to communicate with their hosts is “don't bother, it will get you nowhere”. The host will insist that they are doing everything right for security reasons and the developer should change their software. We can't magically make the raw binary data of the backup archive look like something different so there is nothing we can do. This is exactly why we give you the option to do a manual transfer and we do tell you that the Site Transfer Wizard IS NOT the only way to transfer data between servers, it's just one of your options. In fact, it's one that's limited by your host's serve configuration.
We would much rather skip over the part where all three parties — you, your host and us — get mutually frustrated with each other and just come to the conclusion: if using STW won't work for your environment use a different method; we give you so many options exactly so that there is at least one viable method for your environment. It doesn't mean that every single method should work on every single environment. That's unrealistic.
I hope that helps put some context into Davide's reply and show you that we are not telling you we can't help you, we just know how this pans out based on our experience.
PS: In the past I had thought about implementing appending to files via FTP, something supported by PHP. However, the sad fact of life is that not all FTP servers support appending to files and there was no good way to find that out in advance. Bummer. The only remaining option for chunked upload was via HTTP which can be limited by the host. That's when I created the Import from URL and Import from S3 features in Kickstart Professional which allows the target server to PULL the backup archive in small chunks, something far less likely to be limited and even if it is it's much, MUCH easier to ask the host to fix (basically: ask them to add an exception in their proxy or firewall) without undue complaints. Davide knows this and recommended this method because it's overall the best one and the one we use ourselves for our own sites. 😉
Nicholas K. Dionysopoulos
Lead Developer and Director
🇬🇷Greek: native 🇬🇧English: excellent 🇫🇷French: basic • 🕐 My time zone is Europe / Athens
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