VirtualBoxにあるCentOS7で[Insert Guest Additions CD image...]を押下したら Unable to insert the virtual optical disk となった時の確認方法 - Qiita
Deep Sukhwani Blogs CS50 Appliance - Error \"Could Not Mount The Media/drive \'/Applications/VirtualBox.app/Contents/MacOS/VBoxGuestAdditions.iso\' ( VERR_PDM_MEDIA_LOCKED)\" When Trying To Install VirtualBox Guest Additions | BlogAdda
超電筆記- HackMD
Ubuntu update sonrası VBoxGuestAdditions sorunu (unable to insert the virtual optic disk — VERR_PDM_MEDIA_LOCKED) | by Emel Ergelen (Yıldırım) | Medium
Linuxys: [Solved] Virtualbox: Could not mount the media/drive