Symptoms

The "Admin' and "Preferences" tab are no longer visible/availabe from the plugin repository client.

Cause

The "Data Source" configuration in the "Admin" tab of the repository client has been changed from Proxy Client to Local Generator but the Datasouce URL is still in the form suitable for ProxyDataSource, such as:

http://confluence.atlassian.com/plugin-repository/proxy.action?profile=confluence

Resolution

Run this query on your Confluence database:

select * from bandana where bandanakey like '%atlassian-plugin-repository%';

and look for a similar entry in the query results:

<dataSourceClassName>com.atlassian.plugin.repository.datasource.LocalDataSource</dataSourceClassName>

and update it as follows:

<dataSourceClassName>com.atlassian.plugin.repository.datasource.ProxyDataSource</dataSourceClassName> 

to revert the changes back to using the proxy datasource.