Reduce the number of files in your .article package to 1000 or less. One possibility is to divide the article into two or more articles.
A .article file with more than 1000 files is one known cause for this error to appear. There could be additional causes that have not yet been discovered. If you change the extension of the .article to .zip, you can expand it to view all the files and thus determine if you've reached the 1000 file limit. If not, try removing any non-standard characters used in filenames in your content, such as asterisks.