If you are using Alex popularity plug-in then you might face this error while upgrading plug-in automatically in WP 2.5. This error generate due to invalid wp-header file path in plug-in file. Unfortunately, Alex not released new fixed version of the this popular plug-in. However, fix is really very simple and anyone can fix issue just by editing one single plug-in file. Please follow steps below to fix this error in your installation:
- Deactivate older version of the plugin. If you are installing first time skip this step.
- Download the latest release from wordpress.org or plugin author website.
- Open popularity-contest.php in your favorite editor and scroll down to line 59. Replace
- Save file and upload file to your plugins folder.
- Reactivate the plugin