Question: **The Problem**

When I start Netbeans, it tells me that 21 updates have been found, and I have clickable action to update the IDE:
![Click here to make your IDE up to date.](https://i.stack.imgur.com/TvRcj.png)
![Netbeans IDE Installer](https://i.stack.imgur.com/BmQEr.png)

The install fails and gives me these messages:
![Unable to connect to the Update Center](https://i.stack.imgur.com/CTfSW.png)
![http://updates.netbeans.org/netbeans/updates/8.0/uc/final/distribution/patch11/ide/org-netbeans-libs-svnClientAdapter-svnkit.nbm Not all of the plugins have been successfully downloaded. The server may be unavailable at the moment. Try again later.](https://i.stack.imgur.com/SGUnW.png)

**What I've Tried**

* Disabled anti-virus (AVG)
* Disabled Windows Firewall
* Added Netbeans 8.0 to be allowed by the firewall

**Other**

* Windows 7 - 64 bit

Answer: 
Turns out it was Norton Family that was blocking the connection. My network admin had to disable it temporarily so I could do the IDE update.
For me, neither Antivirus software or Firewall settings were the issue.
However, getting every single update one at a time instead of updating everything in one go worked!

Go to Tools->Plugins-Updates and uncheck everything but one component and then click update. Repeat until done.

Also helps you identify the plugin that breaks the entire update process ... in my case, it was 'Git'.