This is not a valid plugin - But says 2.0 Compatible

I just started using Omeka 2.0.3 and I like it but right now I'm stuck.
I found a list of 2.0 compatible plugins, where Dublin Core Extended was one of them.

I downloaded from and it says Addon version 2.0.
After uploading the plugin to the plugins/ older i get "This is not a valid plugin" when trying to install it from Omeka Admin dashboard.
After checking the forum when i find is that it is missing a plugin.php-file.

Any ideas on how to solve this?

I think this is fixed now. Or at least it's working for me. It may have been an improperly packaged download. I had that issue with another plugin yesterday (where the outer folder was appended with -master).

Same thing. I download the plugin from the "Add-Ons" page, and when i unzip the file, still no plugin.php
This goes for all plugins i whole list of plugins for me?

In Omeka 2.0, plugins are not required to have a plugin.php file, so the issue is something else, and I haven't been able to reproduce this.

That error sometimes happens when the permissions don't allow the server to read all the files, so might be worth checking that.

The permissions seems to be the problem! There were no read access. Now it is working! Thank you!

I had the same problem installing the PBCoreElementSet plug-in, but removing the '-master' from the folder name allowed it to be recognized. Its working now!

I was having this problem and found the answer - it has to do with permissions and can be fixed (on a Debian or Ubuntu Linux server) with the chown command.

Open a terminal and enter the command:

sudo chown -R www-data:www-data /var/www

sudo chown is the command to change ownership in Linux

-R is a command to apply permissions recursively, so the command applies to all folders from the /var/www folder on down

www-data is the username associated with your Apache2 web-server

/var/www is the web-server folder on a Linux machine

Run this command AFTER you close your browser, unzip the plugin and add it to your Plugins folder. Then reopen your browser and log back into your site and the "this is not a valid plugin" error should be gone.

Another thing that I have found is the naming convention of the folder for the plugin, between what github needs and what omeka reads. If it has Master in the name, it needs to be removed. I've had to do for all of the plugins I've downloaded from github. Also, make sure the php file for the plugin matches in terms of the folder/plugin name. I found one that was misspelled (sorry, I don't remember which now)