OEM Agent Home Page Shows ” Communication between the Oracle Management Service to the Agent is unavailable. Any features or displayed information requiring this communication will be unavailable”

After OMS upgraded to 13.4, the agent home pages are showing the following error:

Communication between the Oracle Management Service to the Agent is unavailable. Any features or displayed information requiring this communication will be unavailable

WORKAROUND

This is known issue because of SSLCipherSuites compatibility issue between OMS and Agents after OMS upgrading.

Run the following commands on EM agent server to resolve this issue:

$ emctl status agent

$ emctl pingOMS

$ emctl getproperty agent -name SSLCipherSuites
Oracle Enterprise Manager Cloud Control 13c Release 2
Copyright (c) 1996, 2016 Oracle Corporation.  All rights reserved.
SSLCipherSuites is unset; default value is SSL_RSA_WITH_RC4_128_MD5:SSL_RSA_WITH_RC4_128_SHA:SSL_RSA_WITH_3DES_EDE_CBC_SHA

$ emctl setproperty agent -name SSLCipherSuites -value TLS_RSA_WITH_AES_128_CBC_SHA:TLS_RSA_WITH_AES_256_CBC_SHA:RSA_WITH_AES_256_CBC_SHA256
Oracle Enterprise Manager Cloud Control 13c Release 2
Copyright (c) 1996, 2016 Oracle Corporation.  All rights reserved.
EMD setproperty succeeded

$ emctl getproperty agent -name SSLCipherSuites
Oracle Enterprise Manager Cloud Control 13c Release 2
Copyright (c) 1996, 2016 Oracle Corporation.  All rights reserved.
SSLCipherSuites=TLS_RSA_WITH_AES_128_CBC_SHA:TLS_RSA_WITH_AES_256_CBC_SHA:RSA_WITH_AES_256_CBC_SHA256

$ emctl stop agent

$ emctl start agent 

How to Resolve OEM Agent ‘Availability Evaluation Error’

The following commands helped a client to resolve OEM agent “Availability Evaluation Error”. Just run them in sequence until the issue is resolved.

$ ping omshost
$ nslookup omshost
$ emctl pingOMS
$ emctl config agent addinternaltargets
$ emctl secure agent
$ emctl config agent listtargets
$ emctl clearstate agent

$ emctl upload agent
$ emctl reload agent

The agent should show UP now, otherwise continues the following steps:

$ emctl stop agent
$ emctl secure agent
$ emctl clearstate agent
$ emctl secure agent
$ emctl start agent
$ emctl upload agent 
$ emctl reload agent

$ emctl pingOMS 
$ emctl status agent

How to Reinstall and Configure OEM Cloud Control 13c Central Agent 

For some reason, a client has to reinstall OEM central agents in a multi-OMS Oracle Enterprise Manager Cloud Control environment. Certainly the agent has been installed on the same server as the OMS.

First keep a record of the plugins deployed onto the agent already.

$emctl listplugins agent

Then uninstall the agent cleanly as per How to Deinstall OEM Agents in Oracle Enterprise Manager 13C

The next is to install the agent with required plugins deployed.

Now we need discover all WebLogic Domain targes based on the following instructions, and then all those targets will be monitored by the central agent.

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ERROR: com.oracle.cie.gdr.utils.GdrException: Unable to find distribution xml file in distributions directory /tmp/sfx_TbqwSX/Disk1/stage

While upgrading OMS by running the following command, and the errors occur:

$ ./em13400_linux64.bin
Launcher log file is /tmp/OraInstall2021-09-14_10-33-04AM/launcher2021-09-14_10-33-04AM.log.
Extracting the installer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Done
Checking monitor: must be configured to display at least 256 colors.   Actual 16777216    Passed
Checking swap space: must be greater than 512 MB.   Actual 4095 MB    Passed
Checking if this platform requires a 64-bit JVM.   Actual 64    Passed (64-bit not required)
Preparing to launch the Oracle Universal Installer from /tmp/OraInstall2021-09-14_10-33-04AM
====Prereq Config Location main===
...
..
.
ERROR: com.oracle.cie.gdr.utils.GdrException: Unable to find distribution xml file in distributions directory /tmp/sfx_TbqwSX/Disk1/stage



The log(s) can be found here: /tmp/OraInstall2021-09-14_10-33-04AM.
ERROR: Installer execution failed (102).

WORKAROUND

Quit the current installer, and rerun it again:

$ ./em13400_linux64.bin
Launcher log file is /tmp/OraInstall2021-09-14_11-24-24AM/launcher2021-09-14_11-24-24AM.log.
Extracting the installer . . . . . . . . . . . . . . . . . . . . . . . Done
Checking monitor: must be configured to display at least 256 colors.   Actual 16777216    Passed
Checking swap space: must be greater than 512 MB.   Actual 4095 MB    Passed
Checking if this platform requires a 64-bit JVM.   Actual 64    Passed (64-bit not required)
Preparing to launch the Oracle Universal Installer from /tmp/OraInstall2021-09-14_11-24-24AM
====Prereq Config Location main===
...
..
.
***
update handshake state: finished[20]
upcoming handshake states: server change_cipher_spec[-1]
upcoming handshake states: server finished[20]
Tunneling Response Thread, WRITE: TLSv1.2 Handshake, length = 96
Tunneling Response Thread, READ: TLSv1.2 Change Cipher Spec, length = 1
update handshake state: change_cipher_spec
upcoming handshake states: server finished[20]
Tunneling Response Thread, READ: TLSv1.2 Handshake, length = 96
check handshake state: finished[20]
update handshake state: finished[20]
*** Finished
verify_data:  { 76, 49, 93, 34, 108, 97, 161, 214, 175, 4, 221, 224 }
***
%% Cached client session: [Session-5, TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384]
Thread-84, WRITE: TLSv1.2 Application Data, length = 384
Tunneling Response Thread, READ: TLSv1.2 Application Data, length = 1904
Thread-84, WRITE: TLSv1.2 Application Data, length = 384
Tunneling Response Thread, READ: TLSv1.2 Application Data, length = 736
Thread-84, WRITE: TLSv1.2 Application Data, length = 352
Tunneling Response Thread, READ: TLSv1.2 Application Data, length = 96
Thread-84, WRITE: TLSv1.2 Application Data, length = 560
Tunneling Response Thread, READ: TLSv1.2 Application Data, length = 848
Thread-84, WRITE: TLSv1.2 Application Data, length = 832
Tunneling Response Thread, READ: TLSv1.2 Application Data, length = 800
Thread-84, WRITE: TLSv1.2 Application Data, length = 384
Tunneling Response Thread, READ: TLSv1.2 Application Data, length = 176
detachHome was successful.
Logs successfully copied to /u01/app/oraInventory/logs.

After OMS 13.4 Upgrade :Your browser sent a request that this server could not understand

After upgraded OEM from 13.2 to 13.4, the following errors appear on console GUI:

Bad Request
Your browser sent a request that this server could not understand.
Additionally, a 400 Bad Request error was encountered while trying to use an ErrorDocument to handle the request.

SYMPTOMS

emcli errors:

$emcli login -username=sysman
Enter password

Error: Already logged in as user "SYSMAN". Use "emcli logout" to logout the current user.
$ emcli logout
Error: The connection to the OMS is broken or has been actively interrupted by the OMS (usually due to a communication timeout). Check the log files for further details

After upgrading the OMS to version 13.4, all Agents fail to upload with the following error:

$emctl upload agent
Oracle Enterprise Manager Cloud Control 13c Release 3
Copyright (c) 1996, 2018 Oracle Corporation.  All rights reserved.
---------------------------------------------------------------
EMD upload error:full upload has failed: uploadXMLFiles skipped :: OMS version not checked yet. If this issue persists check trace files for ping to OMS related errors. (OMS_DOWN)

Securing the Agent reports the following errors:

$ emctl secure agent
Oracle Enterprise Manager Cloud Control 13c Release 3
Copyright (c) 1996, 2018 Oracle Corporation. All rights reserved.
Agent successfully stopped... Done.
Securing agent... Started.
Enter Agent Registration Password :
Agent successfully restarted... Done.
Securing agent... Failed.

$AGENT_INST_HOME/sysman/log/secure.log reports following errors:

[13-09-2021 22:11:49] USERINFO ::Securing agent...   Started.
2021-09-13 22:12:04,154 [main] INFO  agent.SecureAgentCmd main.309 - emdWalletSrcUrl: https://oem_slb:4900/empbs/wallets/emd
2021-09-13 22:12:04,160 [main] INFO  agent.SecureAgentCmd secureAgent.392 - Querying HTTPS Upload Port of the OMS
2021-09-13 22:12:04,160 [main] INFO  agent.SecureAgentCmd openPage.987 - Opening: https://oem_slb:4900/empbs/genwallet
2021-09-13 22:12:04,457 [main] INFO  agent.SecureAgentCmd openPage.1014 - Response Status Code: 400
2021-09-13 22:12:04,458 [main] ERROR agent.SecureAgentCmd main.368 - Failed to secure the Agent:
java.lang.Exception: Didn't get a OK response from OMS
        at oracle.sysman.emctl.secure.agent.SecureAgentCmd.openPage(SecureAgentCmd.java:1017)
        at oracle.sysman.emctl.secure.agent.SecureAgentCmd.getOMSSecurePort(SecureAgentCmd.java:933)
        at oracle.sysman.emctl.secure.agent.SecureAgentCmd.secureAgent(SecureAgentCmd.java:393)
        at oracle.sysman.emctl.secure.agent.SecureAgentCmd.main(SecureAgentCmd.java:346)

$<gc_inst>/user_projects/domains/GCDomain/servers/ohs1/logs/ohs1.log reports following errors:

[2021-09-13T22:24:28.4358+10:00] [OHS] [ERROR:32] [OH99999] [ossl] [client_id: xx.xx.xx.xx] [host_id: oms_host1] [host_addr: xx.xx.xx.xx] [pid: 30107] [tid: 140213158373120] [user: oracle] [VirtualHost: oem_slb:0] OHS:2079 Client SSL handshake error, nzos_Handshake returned 28860(server oem_slb:443)
[2021-09-13T22:24:28.4358+10:00] [OHS] [ERROR:32] [OH99999] [ossl] [host_id: oms_host1] [host_addr: xx.xx.xx.xx] [pid: 30107] [tid: 140213158373120] [user: oracle] [VirtualHost: oem_slb:0] OHS:2171 NZ Library Error: SSL fatal alert

CAUSE and SOLUTION

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