I downloaded the .dmg for Firefox, clicked on it, was prompted to drag it to the Applications folder, did so, but cannot launch it.

The directions are to drag the icon from Applications to the dock...but I only see the .dmg file in Applications. How do I know that it installed correctly?

It's in the folder:

Darrens-MacBook-Pro:~ thufir$ 
Darrens-MacBook-Pro:~ thufir$ ls /Applications/Firefox\ 36.0.1.dmg 
/Applications/Firefox 36.0.1.dmg
Darrens-MacBook-Pro:~ thufir$ 

and before I dragged it with the mouse, the OS confirmed the .dmg file.

Type of Mac:

  Model Name:   MacBook Pro
  Model Identifier: MacBookPro9,1
  Processor Name:   Intel Core i7
  Processor Speed:  2.3 GHz
  Number of Processors: 1
  Total Number of Cores:    4
  L2 Cache (per Core):  256 KB
  L3 Cache: 6 MB
  Memory:   4 GB
  Boot ROM Version: MBP91.00D3.B08
  SMC Version (system): 2.1f175
  Serial Number (system):   C02HH5JQDV33
  Hardware UUID:    FBB1FF0A-6EAC-5423-9E8F-405B181EF5F3
  Sudden Motion Sensor:
  State:    Enabled

Here's where I'm at:

step 3

  • 1
    Have a look at: How to download and install Firefox on Mac Mar 14, 2015 at 22:34
  • yes, I'm on step 3. reading it carefully, thanks; will unmount it, also.
    – Thufir
    Mar 14, 2015 at 23:10
  • You drag the Firefox app to /Applications not the .dmg
    – mmmmmm
    Mar 14, 2015 at 23:21
  • what is the "firefox app"? I see "Firefox .dmg" with a hard drive icon...
    – Thufir
    Mar 15, 2015 at 0:57
  • 3
    That window with a blue background with the Firefox app and a large grey arrow pointing to an alias of the Applications folder indicates that you drag the Firefox icon onto the alias of the Applications folder. The Firefox app will then copy into the Applications folder. You seemed to have dragged the .dmg file into the Applications folder.
    – IconDaemon
    Mar 15, 2015 at 1:13

1 Answer 1


You can drag your new Firefox Application directly to the Applications folder.
The folder shown on that blue window is for convenience, a 'shortcut' to your own apps folder.

Either way, you need to drag the actual Firefox app [Application, though the .app is hidden by the system, like on Windows], not its container the .dmg file.

A .dmg is a convenient & secure method of getting an app to you from the developer. It is a self-checking structure, so it knows if it was downloaded correctly & won't open if it's broken. It's a bit like a zip file except that you can 'see' straight into it without unpacking to a new folder…. but like a zip file you need to get the contents out of it before you can use them.

Think of a .dmg as having 3 'stages'…

  • stage 1 - the original .dmg file - when you double click that
  • stage 2 - it mounts a virtual disk on your desktop, which will open to show something along the lines of your blue window.
    [They're not always as nicely set out as that one & they don't always open automatically, sometimes you have to double-click the virtual disk to open it]
  • stage 3 - You then take the contents [your shiny new app] & either drag directly to your Applications folder or a convenient shortcut in the same window.
    Sometimes you need to double-click that 'application' to launch a separate installer.
    You will [almost] always be told which to do.

Once the Application has copied itself to the Applications folder, you then can 'put away' the virtual disk.
You can do this by dragging it to the trash. Disks are not erased by dragging to trash on Mac OS, they are ejected.
Alternatively, you can right click & Eject, or select & hit Cmd ⌘ E

If you want your new app to have a place in the Dock, you can now drag the version in your Applications folder to the Dock & it will add to it.

Once you're happy it all worked, you can delete the .dmg file

Sorry if this explanation is over-simplistic - I just thought it deserved a canonical answer

  • The step by step directions in How to download and install Firefox on Mac are quite explicit and specific in both pictorial and written forms and it's very sad any further explanation is needed! Mar 15, 2015 at 14:42
  • the image in step 3, I didn't take that literally, but as a guide to drag to the actual folder. So, I dragged it to the Applications directory, manually. To me, it's weird to see a popup in a way no other file browser shows files..but that's me. It's different from anything I've ever seen before.
    – Thufir
    Mar 16, 2015 at 7:22
  • I can imagine the possibility for confusion, if you're new to Mac. It works because an alias/shortcut can be made generic, so it will work on anybody's machine [assuming they never moved their original Applications folder, which no-one really ever does] You can also make a folder with a background, which is why the blue with Firefox written in white & the arrow; & you can set things like icon size independently, hence the huge dinner-plate sized icons in that window.
    – Tetsujin
    Mar 16, 2015 at 7:37

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