The plugin does not have a valid header
The plugin does not have a valid header.
–O plugin não possui um cabeçalho válido.
– El plugin no tiene una cabecera válida.
– Das Plugin hat keinen validen Header.
This error appears when WordPress can't delete the folder with previous version of the plugin. There are also cases when cached list of plugins do not correspond with folders available in /wp-content/plugins/. Normally it helps to delete the folder with the problematic plugin and try install it again. You can also check this blog post with alternative solution.
Open your website directory in FTP editor. Navigate to /wp-content/plugins/. Find the folder with the problematic plugin and delete it.