We are having some issues being unable to upload images to CiviMail. This only seems to happen on Chrome (52 on OSX, but perhaps not exclusively), while the same user has no issues in Safari. Seems to affect some users all the time, but not others with similar setups, and other users intermittently.
These two messages are logged for user Anonymous (though the user is obviously logged in):
LOCATION https://secure.wildsight.ca/sites/secure.wildsight.ca/modules/civicrm/packages/kcfinder/upload.php?cms=civicrm&type=images&CKEditor=crmUiId_1&CKEditorFuncNum=3&langCode=en
REFERRER
MESSAGE $Fatal Error Details = Array ( [message] => You must be logged in with proper permissions to edit, add, or delete uploaded images. [code] => )
LOCATION https://secure.wildsight.ca/sites/secure.wildsight.ca/modules/civicrm/packages/kcfinder/upload.php?cms=civicrm&type=images&CKEditor=crmUiId_1&CKEditorFuncNum=3&langCode=en
REFERRER
MESSAGE $backTrace = #0 /var/www/civicrm/4.6/CRM/Core/Error.php(364): CRM_Core_Error::backtrace("backTrace", TRUE) #1 /var/www/civicrm/4.6/packages/kcfinder/integration/civicrm.php(68): CRM_Core_Error::fatal("You must be logged in with proper permissions to edit, add, or delete uploade...") #2 /var/www/civicrm/4.6/packages/kcfinder/integration/civicrm.php(140): checkAuthentication() #3 /var/www/civicrm/4.6/packages/kcfinder/core/bootstrap.php(39): require("/var/www/civicrm/4.6/packages/kcfinder/integration/civicrm.php") #4 /var/www/civicrm/4.6/packages/kcfinder/upload.php(15): require("/var/www/civicrm/4.6/packages/kcfinder/core/bootstrap.php") #5 {main}
Civi 4.6.18, Drupal 7.44