I have a zip archive of ~250Mb located on an Apache HTTP server. Several users have complained of a "corrupt zip folder" after downloading the file directly from the website (albeit the site is built on Drupal but it is using the public download method so it should be a direct download)
The error message when they try to open it in Windows is:
The compressed (zip) folder is invalid or corrupted
I have tried this myself on Windows XP and using both Firefox 14 and IE8. Sometimes it downloads and opens correctly, sometimes I get the error.
Another user is on Windows 7 and using Internet Explorer and has got this message after several download attempts.
When I download via FTP using Filezilla I can open the zip file without errors.
As FTP and HTTP download works at times, then I assume the file on the server is not corrupted but something happens during download and re-uploading the file would not fix anything (and I have tried this).
I created the zip file using IZArc but I am not so sure the method of creation is relevant in this case as it sometimes works.
- What causes the above error messages?
- Why does it happen some of the time and not all of the time?
- What could I do to ensure zip files open without any errors in future?