An update is already in progress. It is normal that the update progresses only slowly since it only refreshes data in small chunks each time a user accesses the wiki. To finish this update more quickly, you can invoke the MediaWiki maintenance script runJobs.php (use the option --maxjobs 1000 to restrict the number of updates done in one batch). Estimated progress of current update:
MediaWiki:Smw smwadmin datarefreshprogress
From Metabolonote
