Missing zlib extensions on Ubuntu

  • Posted February 22, 2015

I have a Wordpress install on a 512Mb Ubuntu 14.04 x32 which is working fine 95% of the time, however I occasionally get this error when both browsing and working in the Admin panel:

Abort class-pclzip.php : Missing zlib extensions

URL here

Can anyone help me identify what this might be? My guesses at this stage are pointed towards a plugin dependency, or php extensions but I want to confirm before playing with the config.

Cheers, Andy


I did the same thing, its still the same.

I am having the exact same issue.

When I run:

php -r 'var_dump(function_exists("gzopen"));'

in the command line, it returns bool(false).

I ran:

sudo apt-get install --reinstall zlibc zlib1g zlib1g-dev

to make sure zlib is installed properly, but it’s still bool(false)

Any suggestions on how to fix this?

It seems some plugin is trying to use class-pclzip.php to compress or extract an archive. It might be a bug in the plugin or a missing dependency. Though, Zlib support should exist by default in Ubuntu. On the command line, what’s the output of:

 php -r 'var_dump(function_exists("gzopen"));'

It should show bool(true) if the zlib extension is available.

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For wordpress create a file /wp-content/mu-plugins/gzopen.php with the content:

if (!function_exists('gzopen') && function_exists('gzopen64')) {
    function gzopen($filename , $mode = 'r', $use_include_path = 0 )
        return gzopen64($filename , $mode, $use_include_path);