macOS High Sierra App Store stuck on blank white screen

1. Your date and time is wrong (this is the #1 culprit)

I know, it sounds dumb. But the App Store on High Sierra absolutely refuses to load if your Mac's date and time is more than a few minutes off. The connection to Apple's servers uses TLS certificates, and if the system clock is out of sync, the certificate check fails. You get a blank white window, or it just spins forever.

Here's how to fix it:

1. Open System Preferences > Date & Time.
2. Click the lock to make changes. Enter your admin password.
3. Check Set date and time automatically. Make sure the server is set to time.apple.com or your region's Apple time server.
4. Wait 10-20 seconds. The clock should snap to the correct time.
5. Close System Preferences and relaunch App Store.

If the App Store loads now, you're done. This fixes about 70% of all High Sierra App Store issues. If not, move to the next fix.

Why this happens: High Sierra's date/time sync sometimes breaks after a long sleep or if you've manually changed the time for another app. Even a 2-minute drift can kill App Store connectivity.

2. App Store cache is corrupted (happens more than you'd think)

The App Store caches metadata locally, and that cache can get corrupted. This is especially common if you've had a crash or force-quit the App Store at some point. The symptom is the same: blank white screen, or it loads partially then hangs.

Clearing the cache is safe. The App Store rebuilds it on next launch. Here's the exact folder path:

~/Library/Caches/com.apple.appstore

To clear it:

1. Open Finder.
2. From the menu bar, click Go > Go to Folder... (or hit Cmd+Shift+G).
3. Type ~/Library/Caches/com.apple.appstore and press Return.
4. Delete EVERYTHING inside that folder. Drag it to Trash, but don't empty Trash yet until you know it worked.
5. Relaunch App Store.

If it loads now, empty the Trash. If not, don't bother restoring those files — they were already broken.

One more thing: Some people also clear ~/Library/Cookies/com.apple.appstore.plist. I've rarely seen that help, but it's an option if you're stuck. Delete that file, restart App Store.

3. NVRAM/PRAM reset (fixes deeper time/network issues)

Sometimes the date/time fix alone doesn't stick because the machine's NVRAM (non-volatile RAM) has corrupted time zone or network settings. This is especially true on 2015-2017 MacBook Pros and iMacs running High Sierra. The App Store will load once after fixing the date, then break again after a reboot.

Here's how to reset NVRAM on an Intel Mac:

1. Shut down your Mac completely.
2. Press the power button, then immediately hold Option + Command + P + R.
3. Hold for about 20 seconds. You'll hear the startup chime twice (or see the Apple logo appear and disappear twice on newer models).
4. Release the keys. Let the Mac boot normally.

After the reset, go to System Preferences > Date & Time and make sure Set date and time automatically is still checked. Then try the App Store.

Note: On Macs with the T2 chip (2018 and later), NVRAM reset is slightly different — you hold the power button instead, but High Sierra doesn't run on those. This reset works for all High Sierra-compatible Macs (2009-2017 models).

Quick-reference summary

One last thing: If none of these work, you might have a deeper network issue — check if your router is blocking Apple's CDN (looks up xp.apple.com). Or run sudo killall -HUP mDNSResponder in Terminal to flush DNS. But honestly, 9 times out of 10 it's just the clock or the cache. Don't go reinstalling macOS unless you've tried all three steps above.