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