Forum Answered Upgrade problem: Due to the following errors, the install/upgrade can not continue:
 

When upgrading one of my forums recently, when I ran the upgrade.php script I got the following message in my browser;

Due to the following errors, the install/upgrade can not continue:
Following is a list of files that are either missing or contain unexpected contents. The most likely cause is that all of the files from this release have not been properly uploaded. You should resolve this error before continuing.
/clientscript/ckeditor/ckeditor.js - File does not contain expected contents
/clientscript/ckeditor/ckeditor_basic.js - File does not contain expected contents
/clientscript/ckeditor/lang/_languages.js - File does not contain expected contents
/clientscript/ckeditor/lang/af.js - File does not contain expected contents
/clientscript/ckeditor/lang/ar.js - File does not contain expected contents

There was a long list of .js files!

I first searched the forums, and while it was clear that other people experienced the same problem, there did not appear to be any definitive answers.

I tried re-uploading the files again, unzipping them again, even downloading them from vbulletin again. All to no avail.

It turned out that the problem was caused by my FTP client, WinSCP. When I uploaded the files again using Filezilla (v 3.5.1) the vbulletin 4 upgrade process completed without any problems or warnings.

I didn't suspect WinSCP because I have been using it for years and always found it to be reliable, so maybe it is a recent upgrade of WinSCP that introduced this problem.

I hope this helps a few people :)