Starting with Java 8, the Permgen memory was removed. This was a location of memory used by previous java versions to store permanent memory objects that won't change durring the running of the application such as java classes.
Java 8 got rid of Permgen and moved all of this information into a new section called "Metaspace" located in the main memory heap. So, a "Metaspace" exception is thrown when java 8 runs out of memory while trying to load data into the Metaspace area of the main memory heap.
So to resolve this exception one of two things need to be done:
1) Allocate more memory to QIE if available.
2) Decrease the number of running threads (processor threads and completion threads). These settings can be found in the "System Configuration" page under the advanced settings.