Premature end of script headers

Knowledgebase

Errors & Troubleshooting | Updated 2026

"Premature end of script headers" is an Apache error that appears in your error log when a CGI or PHP script crashes before it can output the required HTTP headers. The browser typically sees a 500 Internal Server Error. Here are the common causes and fixes.

In This Guide

File Permissions
Line Endings (Windows vs Linux)
Missing or Incorrect Shebang Line
PHP Errors
Output Before Headers

Most Common Causes

Permissions, line endings, or PHP errors

Check the error log first: cPanel > Metrics > Errors. The line immediately before the "premature end" message usually tells you the actual problem (permission denied, syntax error, etc.).

01. File Permissions

CGI scripts (.cgi, .pl) must be executable. Set permissions to 755:

chmod 755 script.cgi

PHP files should be 644 (not executable). If a PHP file is set to 755, some server configurations reject it.

Directories should be 755. Do not use 777 for anything.

02. Line Endings (Windows vs Linux)

If you wrote or edited a CGI script on Windows and uploaded it via FTP in binary mode, the file may have Windows-style line endings (\r\n) instead of Unix-style (\n). The extra carriage return character makes the shebang line (first line) invalid.

Fix: Re-upload the script in ASCII mode, or convert it on the server:

sed -i 's/\r$//' script.cgi

For more on transfer modes, see ASCII vs Binary.

03. Missing or Incorrect Shebang Line

CGI scripts must start with a shebang line pointing to the correct interpreter:

#!/usr/bin/perl

or for Python:

#!/usr/bin/python3

This must be the very first line of the file with no spaces or blank lines before it. Check Server Paths for the correct paths on our servers.

04. PHP Errors

A PHP fatal error (syntax error, missing file, undefined function) causes the script to crash before outputting headers. Check your error log for the specific PHP error:

cPanel > Metrics > Errors
Or check ~/public_html/error_log

See Error 500 - Internal Server Error for PHP debugging steps.

05. Output Before Headers

If your script outputs any text (even a blank line or whitespace) before the Content-type header, you get this error. In PHP, this means any content before <?php or after ?> in included files. A common culprit is a UTF-8 BOM (byte order mark) at the start of the file.

Fix: Make sure there is no whitespace before <?php, and consider omitting the closing ?> tag (which is actually recommended practice in PHP files that contain only PHP code).