What is the current value of this read-only pref? *places.history.expiration.transient_current_max_pages You can create a new Integer pref named <b>places.history.expiration.max_pages</b> if you want to modify the automatically calculates number of pages as stored in places.history.expiration.transient_current_max_pages. Be cautious though with modifying the value of this pref. You can open the <b>about:config</b> page via the location/address bar. You can accept the warning and click "I accept the risk!" to continue. *https://support.mozilla.org/en-US/kb/about-config-editor-firefox