WordPress Plugin Does Not Have a Valid Header

Ran into a problem with installing a plugin today that returned a "Plugin does not have a valid header" message in WordPress. I guessed the problem almost instantly but I figured I would share the solution for anyone that might be searching for it.

Apparently there have been problems in at least one version of WordPress where an automatic update caused this error but in most cases the error is probably due to the folder structure of the plugin you just installed. In my particular case the plugin I was trying to install was in a folder...something like pluginname-20. Within this folder was another folder named pluginname.

WordPress needs at least the basic plugin file to be in the first folder it checks for the plugin so the solution was to upload only the folder named "pluginfolder" with all contents. The pluginname-20 folder was unnecessary and I really am not sure why the plugin was submitted that way.

This problem is easy to run into if you're using something like the One Click Plugin Updater plugin. The plugin lets you install other plugins by uploading the zip files directly and you may not catch the weird folder structure.