Comment 6 for bug 359997

I just had this today...

It also got me really confused.

The popup clearly says:
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Please print or write it down and store it in a safe location. You can run the "ecryptfs-unwrap-passphrase" command now to do this. Enter your user password at the "Passphrase" prompt.
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So I did...
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$ ecryptfs-unwrap-passphrase
Passphrase: [password]
Warning: Using default salt value (undefined in ~/.ecryptfsrc)
Error: Unwrapping passphrase failed [-5]
Info: Check the system log for more information from libecryptfs
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It should be clearly indicated the command to run is:
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ecryptfs-unwrap-passphrase $HOME/.ecryptfs/wrapped-passphrase
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