I tried installing mavericks and i always get "This copy of the Install OS X Mavericks application can't be verified. It may have been corrupted or tampered with during downloading."

Could someone put a detailed explaination of how to fix the date issue via Terminal?

Much appreciated!

First, how are you installing it? Fresh install from a bootable USB? Or are you doing it within OS X?

I'm glad it worked for you too! I'm not sure how Jonathan figured that out. I wanted to post a thank you on his blog, but unfortunately it doesn't allow comments.

I am trying to install it via upgrade from OSX.

Coming from OS ML so not sure why there is such a problem upgrading!

Thanks in advance!

Thank you Bill_04...this worked great on a clean install!

I really would like to do this reset but for some reason Terminal is denying me permission to this command?? Just frustrated all around

Hmm, this blog post indicates an issue installing from a bootable medium. I am trying to upgrade from an existing 10.7 install, and getting the corrupt message. So the date and time are correct. Any ideas?

AppleCare said it could be because I tried downloading over WiFi, so I connected it to a wire. First attempt failed, and said I had to try again (of course started over). WiFi, I tried 5 downloads. It's getting very frustrating!

2 other MacBook Pros, when I "purchase" Mavericks in App Store, it never downloads. I click the "Download" button and a little swirly animation in the upper left corner appears for 10-20 seconds, then goes away and the download never starts. Tried rebooting, not sure what else to try.

So the one MacBook Pro I was able to download on, says it is corrupted. Should I try to locate a big-enough usb flash or hard drive, create a bootable install, and try it from there?

I had this problem also, took me 13 attempts to get to it. finally got it now..
as annoying as this sounds, i agree with everyone else with being patient.

My problem was downloading. I downloaded 6 times over WiFi, no go. The strange thing, is it said the download was complete, but corrupted. When I disabled WiFi and connected a wire, the download failed at 2/3 through, then I continued, and it finished. The downloaded file over wire installed. Hope that helps!

Now thats the ticket! Using the advice from mbanayosi the sudo date entry in terminal resolved the problems and I am downloaded and fully installed to X Big thanks and really appreciate the information getting shared here.

This solved my problem, tks!

I've been having the same problem for 2 days now (about 12-15 tries). Apple Support suggested shutting down and restarting in Safe Boot mode (hold down Shift key right afte4r hitting power on). It seems to have solved my problem.

I downloaded 10.7 and 10.8 with no issues, client and server. 10.9 seems to be flakey, prone to performance issues on the download. I am not surprised that Safe Mode seems to give better results. When you reboot, do you have the checkbox checked to reload all the running apps? At least once in a while, you should uncheck it, so that you get a clean startup. Lots of unseen processes are running in the background that would be restarted if you had it checked.

Also if you caught my comment above, I switched from WiFi (n) to gigabit wired, that did the trick.

Another good health check, perhaps once a quarter or at least twice a year, is to boot and reset NVRAM, PRAM, and the System Management Controller - you can Google the keystrokes on bootup to do these. I have noticed a big jump in performance after doing all these suggestions.