No mountable file systems? Is there any trick to fix the second error? IPad, and Mac platforms. Disable DMG Verification in El Capitan GM. Due to the occurrence of this very error, the user would not be able to install any kind of software in the Mac OS X operating system because the.dmg file cannot be loaded. Heimdall Mac Dmg No Mountable File SystemsĬause of No Mountable File Systems.