Failed to verify the preflight file. It is not signed by Apple.

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I'm not the OP, but I've been having the same problem for weeks. Console output when I try looks like:

10/11/13 12:20:13.339 PM storeagent[476]: -[ISURLOperation _logRequest:]: Sending request for http://a933.phobos.apple.com/us/r1000/104/Purple2/v4/94/0a/95/940a9566-7810-8c99 -c8c8-e82e1e8f3c90/signed.dcr.549627933164448382.pfpkg

10/11/13 12:20:13.344 PM storeagent[476]: -[ISURLOperation _handleReceivedResponse:]: Received headers for http://a933.phobos.apple.com/us/r1000/104/Purple2/v4/94/0a/95/940a9566-7810-8c99 -c8c8-e82e1e8f3c90/signed.dcr.549627933164448382.pfpkg

10/11/13 12:20:16.509 PM storeagent[476]: *** Assertion failure in -[ISCheckPreflightOperation verifyDistributionAtURL:allowsDevSign:allowsUnsigned:osVersionToBeInstalled:err or:distributionController:], /SourceCache/Pisa/Pisa-232/ISCheckPreflightOperation.m:314

and AppStore.log looks like:

Oct 11 20:27:43 CalMac.local storeagent[476]: ISCheckPreflightOperation: remote pre-flight downloaded to file:///var/folders/w_/vp6f0qvx5s733hrxjr5ftcyc003j7d/C/com.apple.appstore/4089 81381/preflight.pfpkg

Oct 11 20:27:43 CalMac.local storeagent[476]: ISCheckPreflightOperation: Running local pre-flight from file:///var/folders/w_/vp6f0qvx5s733hrxjr5ftcyc003j7d/C/com.apple.appstore/4089 81381/preflight.pfpkg

Oct 11 20:27:46 CalMac.local storeagent[476]: file:///var/folders/w_/vp6f0qvx5s733hrxjr5ftcyc003j7d/C/com.apple.appstore/4089 81381/preflight.pfpkg is not signed by Apple Error Domain=PKProductErrorDomain Code=0 "The operation couldn’t be completed. (PKProductErrorDomain error 0.)" UserInfo=0x7f975a404820 {PKTrustLevel=2, NSUnderlyingError=0x7f975c886630 "The operation couldn’t be completed. general network error"}

Oct 11 20:27:46 CalMac.local storeagent[476]: ISCheckPreflightOperation: verified preflight success=0, error=Error Domain=ISCheckPreflightOperation Code=0 "Failed to verify the preflight file. It is not signed by Apple." UserInfo=0x7f975c8a9560 {NSUnderlyingError=0x7f975c8c5060 "The operation couldn’t be completed. (PKProductErrorDomain error 0.)", NSLocalizedFailureReason=Distribution file "file:///var/folders/w_/vp6f0qvx5s733hrxjr5ftcyc003j7d/C/com.apple.appstore/408 981381/preflight.pfpkg" is not signed by apple, NSLocalizedDescription=Failed to verify the preflight file. It is not signed by Apple.}, distController=(null)

Oct 11 20:27:46 CalMac.local storeagent[476]: ISCheckPreflightOperation: Error found checking preflight - Error Domain=ISCheckPreflightOperation Code=0 "Failed to verify the preflight file. It is not signed by Apple." UserInfo=0x7f975c8a9560 {NSUnderlyingError=0x7f975c8c5060 "The operation couldn’t be completed. (PKProductErrorDomain error 0.)", NSLocalizedFailureReason=Distribution file "file:///var/folders/w_/vp6f0qvx5s733hrxjr5ftcyc003j7d/C/com.apple.appstore/408 981381/preflight.pfpkg" is not signed by apple, NSLocalizedDescription=Failed to verify the preflight file. It is not signed by Apple.}

(I'm aware the timestamps don't match, they're from different attempts.)

System software updates (Java etc.) work fine. I just can't update or install regular apps.

I have an identical problem except that it occurs with Apple's iWork and iLife suites which were all purchased from Apple (but before the Mac App Store). Message:

Have tried various remedies, but it looks as if I'll have to call Apple Support.

In my case, I've been able to work around it by signing into my admin account (instead of my regular user account) and installing/updating from there. Had hoped that might fix some permissions or something for my regular user, but it hasn't.

Next step: fresh install of 10.9 that I've just downloaded, as it was the developer preview I was experiencing this issue on. Fingers crossed...

(FWIW, installing the public version over the top of my developer version didn't help.)

This is what I get on my Console

10/23/13 11:33:59.253 AM storeagent[344]: *** Assertion failure in -[ISCheckPreflightOperation verifyDistributionAtURL:allowsDevSign:allowsUnsigned:osVersionToBeInstalled:err or:distributionController:], /SourceCache/Pisa/Pisa-232/ISCheckPreflightOperation.m:314

What worked for me was changing the certificate preferences in Keychain Access (open Keychain Access app and then go to preferences).

I just changed both of the first two options to 'Best Attempt', they were originaly at 'Require if certificate indicates'.

Hope this Helps

I´ve tried anything for months. The issue came first time with Mountain Lion, here as sandboxing began.

Now I tried the keychain access solution and all is woprking fine.

Thank you

Quackie, your my idol, woks fine, many thanks. Just a just a question.. Is there any security issue by modifiying the settings to Best Attempt? Thanks again.

Sorry Quackie, the idol message was P1991atric of course, but I am happy that his solution worked for you too. Great community!

I don't know what the security differences are exactly, but you can always change it back to what it was after you update.

This solved the issue. It worked like a charm. Thanks!!!