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App store is failing to update apps, with verification error

For the past week or so, I've had numerous updates in the App Store which I can't update. I first noticed this when trying to update Evernote. As other updates have become available, none of them will update. This is with App updates. The system updates seem to work fine, except the Pro Video Formats, mentioned below.


If I try to update from the UPDATES page, every time I get the message:

We could not complete your update.

The product distribution file could not be verified. It may be damaged or was not signed.


If I try to update from the PURCHASES page I get the error:

Failed to download Numbers. [or whatever app I try to update]

The product distribution file could not be verified. It may be damaged or was not signed. The application will be available from the Purchases page.


and then, after clicking OK


We could not complete your purchase.

The product distribution file could not be verified. It may be damaged or was not signed.


I found some old instructions (from around 2012) saying to resolve a similar issue (on Mountain Lion or earlier perhaps) to do the following:

Enter this into Terminal: open $TMPDIR../C/

find and delete the com.apple.appstore

I did this a few times, with no success.


Today I allowed the Yosemite 10.10.3 update to go through. That worked fine, but did not resolve this issue.


I also notice the Pro Video Formats 2.0.1 update updated during the other system updates, but it is now sitting there are an available update again. Same version number. I can install it again and again. It keeps reappearing. I see other people in the forums having this same issue.


What can I do to resolve this?

MacBook Pro, OS X Yosemite (10.10.3), 256 SSD, 1TB HDD, 8GB RAM, Matt

Posted on Apr 22, 2015 4:34 AM

Reply
2 replies

Apr 22, 2015 1:02 PM in response to InspiredLife

Several causes for this problem have been reported. Please take each of the following steps that you haven't already tried. Stop when it's resolved.

Step 1

If possible, test on another network, such as a public hotspot (if the computer is portable) or the hotspot created by a mobile device. A network gateway that blocks some traffic, most likely on a company or university network, could be causing the error.

Step 2

Back up all data.

From the menu bar, select

System Preferences... Network

If the preference pane is locked, click the lock icon in the lower left corner and enter your password to unlock it. Then click the Advanced button and select the Proxies tab. If any proxy options are selected, make a note of them and then deselect them. You don’t need to change the bypass or FTP settings. Click OK and then Apply. Test. The result may be that you can't connect to any web server. Restore the previous settings if that happens.

Step 3

Rebuild the Spotlight index. If you try to search now from the magnifying-glass icon in the top right corner of the display, there will be an indication that indexing is in progress.

Step 4

Start up in safe mode and log in to the account with the problem. You must hold down the shift key twice: once when you turn on the computer, and again when you log in.

Note: If FileVault is enabled in OS X 10.9 or earlier, or if a firmware password is set, or if the startup volume is a software RAID, you can’t do this. Ask for further instructions.

Safe mode is much slower to start and run than normal, with limited graphics performance, and some things won’t work at all, including sound output and Wi-Fi on certain models. The next normal startup may also be somewhat slow.

The login screen appears even if you usually login automatically. You must know your login password in order to log in. If you’ve forgotten the password, you will need to reset it before you begin.

Test while in safe mode. Same problem?

After testing, restart as usual (not in safe mode) and verify that you still have the problem. Post the results of the test.

Apr 22, 2015 5:54 PM in response to Linc Davis

Thanks. #1 in your answer lead me to think about the network setup on this machine.

I have DNSCRYPT installed and running. This has never been as issue in the past (had it for a year or more).

But, it would seem that it now interferes with some aspect of the App Store authentication process. When I disable it, the issue of not being able to installed updates has gone.


This has also resolved the looping update issue.

App store is failing to update apps, with verification error

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