You have the Microblog up to 5.1.0 and when you delete a space you get the message that it failed and the space cannot be deleted.
The problem can have multiple causes. One cause may be that the space has a Microblog topic with posts and replies or edited posts. Since Microblog 5.1.1 this is no longer an issue.
This update might take several minutes, because it is required to run through all replies and historical versions of posts. We measured around 5 minutes update on an instance with around 16 thousand replies.
The progress can only be tracked by enabling INFO logging for net.seibertmedia.
If you want to check how many replies are on your system, you may want to run this SQL on your database (example made in PostgreSQL):
SELECT count(*) FROM content WHERE pluginkey = 'net.seibertmedia.plugin.confluence.microblog:micropostContent' AND prevver IS NOT NULL AND parentccid IS NOT NULL;
content is the table with any content object in Confluence.
pluginkey is the column that indicates our plugin's Micropost content object.
prevver is a foreign key to the newest version of a post and NOT NULL indicates a historical version.
parentccid is a foreign key to the parent post and NOT NULL indicates a reply.