I get this with some of my php files: Fatal error: Unable to read X bytes in /home/user/public_html/myfile.php on line Y
Solution:
This means that the file was uploaded as ASCII text (plain text) instead of as a binary file (1's and 0's). Some PHP codes require that it is transfered as a binary file and not as plain text. Setting your FTP client to force Binary mode, instead of allowing it to auto-detect the mode, will fix this problem 90% of the time.
