Having trouble installing OS X El Capitan

Downloaded OS X El Capitan from the Apple App Store and having the same problem. Date is correct even after 'ntpdate time.apple.com' or 'ntpdate -u time.apple.com'. Haven't found a solution yet.

BTW, My MacBook is 2015 early MacBook Pro and Everything is updated before install the downloaded OS X El Capitan from usb stick.

OS X is beautiful look-feel, but not smart as Linux and detailed reference manual is insufficiency.

I am facing the same problem. I have downloaded it twice and deleted it twice now, it continues to give me the same Error.

Short story: I now have El Capitan running after numerous problems.

BritinUSA's post gave me an idea... though it wasn't going to a coffee shop, it made me think of something else in between the download file and my computer... rather than getting online wirelessly via my Apple Airport, I connected wirelessly but DIRECTLY to my modem and attempted the download again. Basically I bypassed my Apple Airport device. This time, the downloaded file appeared to be complete (no more error that had plagued me 4 times) and started installing...

... then I received an error message that the install had failed. The worst part: I kept getting the "kernel panic" black screen of death... over and over.

I managed to startup in safe mode (holding shift+command+r while restarting) and reattempted the installation. It took an incredibly long time, but worked this time. That was yesterday morning and all seems to be running well -- in El Capitan -- since.

Since people here were helpful in getting me thinking about things to try, I wanted to come back and post what actually worked... however random it might seem!

Thanks all!!

I downloaded El Capitan three times and overtime I got the "can't be validated" error message. I was trying to do this while at a hotel while traveling. I got home yesterday and then tried it once more and I was able to upgrade on the first try. I am guessing the problem was with the network I was using. Not sure what could have happened, but this resolved the issue for me.

-J

I am running 10.11.1, but it is not installed. No El Capitan in Applications folder. Apple logo says 10.11.1. App store purchases say it is not downloaded yet. I have done this 3 time over 2 days. Having trouble with native apps. Adobe Lightroom running fine. I am just not going to shut down until I get all my work done.

I have the same problem with everyone here, I checked the date and tried to install in safe mode but nothing worked. Then I notice that the installer is only 4.44 gb instead of 6.17 gb as shown in the app store although the purchased page said that the el capitan is downloaded. This is the third time I downloaded the update, the other two times the size was also < 6,17 gb. Is this the problem???

I had the same issue. My fix was to change Energy Saver settings to "never" Computer sleep, "never" Display sleep, and unclick "Put hard disks to sleep when possible.😊

Changing the date through the terminal worked for me. The date was in the year 2001 and then I changed it to the current along with the time. Hopes this helps anyone.

You're a genius, pardon the pun, I have been stuck on this for a day or so!

I got a new HDD and after creating a boot usb stick i got the same message. I opened the terminal and set the date from the little menu present at the Install OS X screen and i ran the date command. The date was set to 2000. I change the date like: date 1124094515 where these numbers represent [mm][dd]HH]MM[yy].

After that initiated the installation script and it's almost done, no more error. Thanks for other people's input on the subject.

I found the answer to this issue was the post by LinkTree on Oct 1, 2015 11:37 PM that mentioned the issue of incorrect time.

Stupid date fix.

Go to Utilities and click on Terminal. To see what time/date your MacBook thinks it is, type "date" and press return. Mine came back as thinking it was 3 am in 2001. To set it to today I typed "date 0110184516" which meant January 10th, 6:45 pm, 2016. It put it into Pacific Standard Time, which I'm not in, but that didn't seem to offend the MacBook or the install USB at all. Installed in 12 minutes, same USB that failed three times before I used Google to figure out this whole DATEGATE issue.

Want to throw in my 2 cents:

I installed an SSD in my 2010 macbook pro. Made a bootable USB on my desktop with El Cap downloaded off the app store. Got the posted error multiple times on multiple USBs. Verified .dmg on the desktop. Verified date on the desktop. Opened terminal in the startup manager on my macbook and date was 2001. Followed above advice to fix.

No more than an annoyance in the end. Think it's interesting that Mac doesn't offer older versions of OS in the App Store, especially considering that El Cap has 3 out of 5 stars. Reminds me of windows 8 or something. Keep supporting at least one really stable older version like Mountain Lion please.

Finally got it working. The date was correct and the file verified, but it still would not install. SOLUTION: set the date to the date when you downloaded the OS X El Captain installer. It is now 2016, when I set the date back to October 2015 everything installed just fine! What an extremely STUPID error message. The file was not corrupt but the check itself failed.

Same error here and thanks to @mikeverk I did it :-) My date too was correct to today (March 14th 2016), but I dunno why it ddint like it. NOw setting to date 1124094515 is installing fine... tnx!