Article ID: 118802, created on Nov 22, 2013, last review on Aug 12, 2014

  • Applies to:
  • Plesk Sitebuilder 4.5 for Linux/Unix


The following error is shown when click "Retrieve Key" on the License Management page (Server > License Management > Retrieve Keys)

Internal Server Error

This error is shown in the log (/var/log/httpd/sitebuilder_error.log):

Premature end of script headers: php5, referer:


Parallels Plesk Sitebuilder 4.5 is installed on server with unsupported operating system, for example CentOS6.

Invalid library libcurl is installed on the server.


There are two ways for to resolve the issue:

  1. Setup new server with supported operating system and migrate Sitebuilder data to new server as advised in this KB article:

    [How to] How to migrate sites and users to another Sitebuilder server?

  2. Replace libcurl with library shipped with CentOS5. On CentOS5 library is provided by package curl-7.15.5:

    ~# rpm -qf /usr/lib/

    On CentOS6 the package is provided by libcurl-7.19.7:

    [root@sitebuilder ~]# rpm -qa | grep libcurl

    Replace the library with from curl-7.15.5, most likely you'll need to downgrade curl package as well.

    Proper rpm package curl-7.15.5 shipped with CentOS5 may be downloaded from the autoinstaller website: CentOS5, 64-bit or CentOS5, 32-bit.

Search Words


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Internal Server Error

unsupported operating system

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