Support » Fixing WordPress » "The plugin does not have a valid header" problem – various plugins

  • I have a problem with a new development site that I am setting up to troubleshoot a site. The URL is the same so there should be no problem with the tables and the site otherwise appears to work OK. I copied the old tree elsewhere, installed from the bottom up – new 3.2.1 install, with themes and plugins installed manually from zips etc.

    When I go to the Dashboard, a few plugins need updating since I have copied older zips. Most of these update OK but Subscribe2 and Wordprees Importer, on updating, report the invalid header error, deactivate themselves and disappear although they are still in the plugins tree. I have seen this before.

    I am puzzled by this as both are current plugins and known to work with 3.2.1 so it must be in the tables. The trouble is, knowing where to find them! Is the information stored in the XX_options table? Or where and how does WP know which plugins (and themes) are available?

    Could someone please direct me!


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  • Further to this, although the plugin does not appear in the dashboard, the directory and tree are not removed. So if I just download a new copy it won’t install. Deleting (rm -rf) the directory allows me to download the updated plugin OK.

    So maybe the idea of copying the plugin tree from elsewhere – or from the downloaded zip file – is not the way to do it, other than that is the original manual approach even if it requires typing rather than clicking.:)

    So this leads me to another question: is there a way to automatically update plugins and themes other than via the Dashboard? ie a script or php program? One would need to select the plugin, deactivate it, remove the old tree, copy the new tree and then reactivate it. There must be a standard for plugins…:)

    Hmm. No comments yet. So here is another question!

    I notice in XX_options there seems to be a number of entries for plugins that are no longer active or were removed just be deleting the tree. This may be the root of the problem – a plugin update may choke if the tables are already present although sometimes this doesn’t matter and sometimes we actually need to preserve some settings.

    I’ve tried Plugins Garbage Collector but that only removes unused tables (and the beta identifies but doesn’t remove unused columns so I used phpMyAdmin to do that). Is there anything that will remove or identify the unused entries in a table?

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