Web Tier重启问题描述：
Oracle Enterprise Manager 12c (12.1.0.2) issues – yodContextUnwrap(,FALSE)
Posted on 22/10/2012
Today we started with the new 12.1.0.2 version of the Oracle Cloud Control on OEL 6.3 (x64), and as soon as I turned on notifications, my inbox filled up with messages about the OGC WebTier beeing down. This was not true, and trying to get control of the webtier in OGC was not possible.
The logs filled up with this message

日志如下：
[2012-10-22T10:28:52.1857+02:00] [OHS] [INCIDENT_ERROR:10] [OHS-501] [mod_context.c] [host_id: xxx] [host_addr: xxx] [pid: 26522] [tid: 139633992931072] [user: oracle] [VirtualHost: main] yodContextUnwrap(,FALSE) failed

During my quest to find a solution to this problem, I also came across a bug that causes logrotate not to work unless you install this package:

yum install compat-expat1.x86_64

But that is a different issue.

Looking into this i noticed that the agent on my Enterprise manager server was still running version 12.1.0.1.
Since I had little or no reference to this error on MOS or in the forums, I thought it might be a good idea to restart my EM, and to
start it with the 12.1.0.2 agent instead.
This issue was not a problem when both the OMS and agent was at the same version.
Upgrading the agent/OMS make sure you are running both at the same version, as Oracle will not alert you to wrong version of the agent being used.
Since starting the 12.1.0.2 agent my issue as been resolved, and that annoying email every 16 sec is gone.

2、日志如下：
<1>OHS.log
WebLogic Server Plugin version 1.1 <WLSPLUGINS_11.1.1.6.0_LINUX.X64_111122.1115.0001>
Oracle-Application-Server-11g/11.1.1.6.0 Oracle-HTTP-Server (Unix) mod_ssl/11.0.0.0.0 OtherSSL/0.0.0 mod_plsql/11.1.1.0.0 mod_onsint/2.0 configured -- resuming normal operations
<2>在OEM12cweb页面上的报错
The HTTP Server instance is down
CLEARED - The HTTP Server instance is up

Solution:
but it clears itself within minutes. Still manages to spam my mailbox.
This started last night after upgrading the Database plug-in to 12.0.3.0.
Oracle Support pointed me to a tech note with titel: Cloud Control 12.1.0.2 : False Alerts about EMGC_GCDomain/instance1/ohs1 Target Down (Doc ID 1496775.1)
This provides a link to a patch (p13490778_111160_Generic.zip). Opatch apply that one on all OMS installs and restart all. Fixed.

--The END--

OEM Web Tier重启问题