Charles runs out of memory
After recording for a while Charles will run low on available memory. To free up memory you should clear the current session.
If you frequently run out of memory you can increase the default heap size.
Windows
Edit C:Program FilesCharlesCharles.ini and change vm.heapsize.preferred to a higher number. Be sure not to remove any other the letters or symbols around the numbers!
Mac OS X
Find Charles.app in your Applications folder, right click and choose Show Package Contents. Open the Contents folder and open Info.plist in a text editor, such as Text Edit. Find VMOptions and change the number in -Xmx256m. Be sure not to remove any other the letters or symbols around the numbers!
Linux
Edit the charles.sh file and change the number in -Xmx256m. Be sure not to remove any other the letters or symbols around the numbers!