Time Machine very slow encrypting after backup

My external HDD (LaCie USB-C 4TB) ist formatted as Mac OS Extended (Journaled, Encrypted) and after the backup finishes the encryption process continues (still not finished the encryption of the initial backup). The progress of this process is extremely slow, about one week for 10% or longer! What is the Problem? MacBook (Early 2016).

What exactly did you do?

I have a 4 TB back up and it's less than 5% done after two days...says, "encrypting". Since my back up is encrypted I don't need Time Machine to encrypt, at least I don't think so. I try to uncheck the encrypting box in Time Machine but it's greyed out.

What you describe is completely normal. It will take the better part of a day to finish encrypting 48 GB with a rotating hard disk drive.

Once it finishes incremental TM backups will take only a moment or two, as usual.

This is the single most important piece of information we need!

If your disk is encrypting for an unbearably long time, cancel it, erase and encrypt the drive first, and than start the timemachine backup. So worth it.

Every previous thread I've read says "yes, the long encryption time is normal, just let it finish” But it is so much better to just stop and erase and encrypt the disk first.

What a huge difference: Before, it was saying 10% encrypted … after 8 hours!
Encrypting with disk utility however takes less than a minute, and now backing up with TimeMachine happens at the usual speed.

Thanks for posting.

I'm having the same exact problem. Actually my first backup completed in an hour or so but the 2nd back up will probably take 24 hours if I let this encryption go on. I've called apple tech support and been to the genius bar, all who have attempted to solve the problem, but every time I go to do the 2nd back up, I'm home alone and their solutions didn't work.

My back up is formatted as Mac OS Extended (JOunaled, encrypted).

Have you found any solutions yet? People are complaining about this in a lot of forums and I'm surprised Apple has not come up with a good answer yet.

I always erase and encrypt the disk before starting my backup, but I've noticed that TM somehow avoids and undoes my effort each time -- it seems to unencrypt or erase the disk, then backs up, then re-encrypts.

This is maddening.

I'm assuming Apple wanted initial backup to be fast, but this is so much worse. And I have a partially encrypted drive in the meantime which is a liability.

To speed up the process of TM encryption, go to Disk Utility, select your external HDD and erase and use the option journaled/encrypted. Once your external HDD is erased, you can redo the backup and the encryption will be as fast as a flash.

I have a2TB external and my initial encryption was going to make 1 week! when I did as described above it took 30m

first you format the disk under Mac OS Extended (JOunaled, encrypted), then when setting up TM you also select "encrypt ". I have a 2TB eternal HDD and I backed up about 600GB in about 15minutes using USB3 connection.

TM shouldn't perform FV encryption with every backup. That's not normal. I'll have to investigate that.

In the meantime you don't need to leave a backup drive connected to a portable Mac all the time. TM performs "local snapshots" that are written to the backup drive when it becomes available, even if that isn't for a few days: About Time Machine local snapshots - Apple Support.

Can you tell me how to cancel the encrypting? There is no option to stop it in the Time Machine Preferences Pane. Thank you in advance for your reply.

I have the same problem. My Time Capsule died after six years. I got a USB drive. Set up Time Machine and checked the Encryption box. It took a while (8 hours or so) but 1TB of data was backed up successfully. But now every time I look at the TM window it says "Encrypting..." Been that way for days.

Doing the encryption at the point of formatting the disk sounds interesting.

Then when you set up TM to that disk do you also click on the Encryption option or not since the disk is already encrypted?

So I finally got around to erasing the disk and formatting it as encrypted from the start - and everything has been working fine and fast since.

Just as I hit the "erase" button out of the corner of my eye I saw that a backup had been completed - this after a recent reboot. So maybe it wasn't necessary to do the extra step of encrypting the drive, maybe just a reboot got TM back to a stable state. I could confirm this with a test, but it's working and that was my goal so no use re-visiting this issue.