When attempting to delete a few images today on the English Wikipedia, in irregular intervals I was presented with an error that stated, "Error deleting file: An unknown error occurred in storage backend "local-swift-eqiad"". So far I've encountered it about 4 times in the span of 2 hours.
There wasn't any commonality with the images that presented the error and the files weren't particularly large. (For instance, one file was only 76 KB.) For all the files where I encountered the issue, when I attempted to delete them again I was successful.