When you transfer files to the server using FTP, these files can be uploaded in two distinct modes: text and binary. As Flash CMS libraries are encoded, they should be transferred in binary mode.

You can tell that you've encountered this issue if you see any of the following:

• Fatal error: Unable to read 2680 bytes
• Fatal error: file is corrupted...
• Empty page or "ERROR 500"
• "Error while saving..." message displayed after control panel setup

To fix this error, set your FTP software to binary transfer mode and upload "admin" folder again.

Here's how to switch to binary mode in common FTP transfer programs:

• FileZilla:
  
• WinSCP:
  
• FTP Commander:
  
• Cyberduck:
  

Following this link you can watch video tutorial about binary mode.