Unfortunately you forgot to attach a ZIP file containing your Akeeba Backup log file. Without it I cannot help you with any backup issue as I have no idea what is going on with your server. If the file is over 2Mb, please upload it on your server and post a link to it. Kindly note that uploaded log files are private, even though the ticket is public. That is to say, only you and us can see attachments on your ticket. Moreover, all attachments are purged 30 days after the ticket is closed.
Based on my experience, the reasons why that would happen are (ranked from most common to least common):
- Your files are not really corrupt, you just didn't read this page which explains why some CRC checksums may appear corrupt. If this is not the case, keep reading.
- You corrupt the download during transfer. If you are downloading them manually please use either SFTP or, if that's not possible, FTP/FTPS in Binary Transfer mode. Don't use your browser.
- Your CRON jobs is killed prematurely by your server. The backup isn't complete, therefore it's corrupt. You can check if your backup log file for that particular backup record contains the phrase "Kettenrad :: Just finished" towards the very end of the file. This phrase indicates the completion of the very last step of the backup process. If that phrase is missing you need to contact your host and ask them to increase the timeout of the CRON daemon, i.e. let your CRON jobs run longer.
- Are you storing your files to remote storage? If your CRON job is killed prematurely by your server you might be at the point where your backup is only half-uploaded. That would, indeed, cause it to be corrupt. This could require either the fix explained above or, if you are using the front-end or JSON API (e.g. a third party service) backup method then you might need to tweak the uploading of your backup archives to remote storage. I need your log file to help with that.
- A far more esoteric reason which is very unlikely but I have seen in a number of cases I can count on my fingers (with fingers to spare!) over the last 12 years such as that case where a misconfigured Apache server was doubling the requests sent to it or when a misconfigured caching proxy in front of the server was sending back a cached response, completely ignoring the "no cache" headers sent by our software. I need your log file to even consider such a possibility.
Nicholas K. Dionysopoulos
Lead Developer and Director
🇬🇷Greek: native 🇬🇧English: excellent 🇫🇷French: basic • 🕐 My time zone is Europe / Athens
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