After installing all the current updates, the updater (choose Help > Check for updates) complains with this error:

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Checking for updates failed.
Check your network connection, verify that your proxy settings are configured correctly in the NetBeans IDE, or try again later.
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Similarly, the Plugins window cannot check for updates. Works when I first install NetBeans, but then fails after all suggested updates are made.

Choose Tools > Plugins > Updates (tab) > "Check for Updates" button. The following error appears.

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Unable to connect to the Plugin Portal because of Connection reset
Check your proxy settings or try again later. The server may be unavailable at the moment. You may also want to make sure that your firewall is not blocking network traffic.
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If I click the "Proxy Settings" button in the error message, I get the Options > General Pane, with "Proxy Settings" set to "Use System Proxy Settings". I click the "Test connection" button, a green check appears next to it.

This problem began after making the latest updates to 8.0.1. This problem did not happen with NetBeans 8.0.0. And did not happen with 8.0.1 until recently.

The problem is reproducible on my Mac OS X 10.8.5 running in a virtual machine under Parallels ( VM has 3 cores, 5 gigs of memory ). Using Java 8 Update 25.

1) Delete NetBeans folder in Applications folder.
2) Delete the "NetBeans" folder at /Library/Application Support/NetBeans
3) Download the Java EE edition of NetBeans 8.0.1.
4) Install 8.0.1, use defaults except turn off Glassfish option and turn on Tomcat.
5) Launch NetBeans
6) Accept offer to update the update.
7) Click ballon to relaunch NetBeans.
8) Accept offer to update many parts of NetBeans. Wait for downloads, watching progress bar.
9) Click balloon to relaunch.
10) Choose Help > Check for updates.
BAM! Bug. Get error message about "Checking for updates failed.". 

Fails at this point consistently. I've done this process twice. So apparently one of those suggested updates is causing the problem. The updater works for two rounds of updates before being rendered incapable.

Here is my log from:
/Users/brainydeveloper/Library/Application\ Support/NetBeans/8.0.1/.metadata/.log

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!SESSION 2014-11-18 01:22:31.557 -----------------------------------------------
eclipse.buildId=unknown
java.version=1.8.0_25
java.vendor=Oracle Corporation
BootLoader constants: OS=macosx, ARCH=x86_64, WS=cocoa, NL=en_US

!ENTRY org.eclipse.core.net 1 0 2014-11-18 01:22:31.557
!MESSAGE System property http.nonProxyHosts has been set to local|*.local|169.254/16|*.169.254/16 by an external source. This value will be overwritten using the values from the preferences
!SESSION 2014-11-18 01:22:57.020 -----------------------------------------------
eclipse.buildId=unknown
java.version=1.8.0_25
java.vendor=Oracle Corporation
BootLoader constants: OS=macosx, ARCH=x86_64, WS=cocoa, NL=en_US

!ENTRY org.eclipse.core.net 1 0 2014-11-18 01:22:57.020
!MESSAGE System property http.nonProxyHosts has been set to local|*.local|169.254/16|*.169.254/16 by an external source. This value will be overwritten using the values from the preferences
!SESSION 2014-11-18 01:24:40.256 -----------------------------------------------
eclipse.buildId=unknown
java.version=1.8.0_25
java.vendor=Oracle Corporation
BootLoader constants: OS=macosx, ARCH=x86_64, WS=cocoa, NL=en_US

!ENTRY org.eclipse.core.net 1 0 2014-11-18 01:24:40.257
!MESSAGE System property http.nonProxyHosts has been set to local|*.local|169.254/16|*.169.254/16 by an external source. This value will be overwritten using the values from the preferences
 
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-Basil Bourque