Oracle 12c Express Enterprise Manager webpage does not load

Problem summary

When browsing to the Oracle 12c EM Express webinterface, the page times-out when using a URL like:

• http(s)://hostname:5500/em

• http(s)://hostname.domain:5500/em

When using a url containing the IP address, or localhost, the page loads, but very very slowly (up to 5 minutes).

• http(s)://ip-address/em

• http(s)://localhost/em

When using the hostname, the listener log shows errors (multiple of these):

03-DEC-2015 11:25:33 * http * (ADDRESS=(PROTOCOL=tcps)(HOST=%14)(PORT=52925)) * handoff * http * 12518
TNS-12518: TNS:listener could not hand off client connection
TNS-12560: TNS:protocol adapter error

When using the IP address or localhost, the listener log shows no errors:

03-DEC-2015 11:23:39 * http * (ADDRESS=(PROTOCOL=tcps)(HOST=)(PORT=52902)) * handoff * http * 0

This problem shows up all over the web (see references in footer), and nobody seems to be able to find the cause of this. I've tried -every- suggestion i could find, and listed the results below. I'll let this great community have a crack at it, and then it's off to Oracle support...

Platform information

• Windows Server 2012 R2 x64

• Oracle 12.1.0.2.0

• A multitenant container database (CDB) with two Pluggable databases (PDB)

• Automatic Storage Management (ASM) is not being used

• Performing tests locally on the server, with firewall completely disabled

Tests already performed

emctl

A lot of people would suggest checking "emctl" out of habit. This does not exist for 12c, as it uses EM Express and not Database control.

http/https

I've set up, and tested this for http and https. No difference.

Browser

I've tested this in vanilla installations of IE 11, chrome and firefox. No add-ons enabled.

Database access

Both the CDB and PDB's can be accessed and queries through SQLPlus

Telnet

Opening telnet connections to the ports (e.g. 5500) works.

Alert log

The Oracle alert log does not contain any error messages.

My hypotheses

• Something related t

What do you get when you run these commands on db host

From command prompt:

ping host
ping ipaddress(host ipaddress)
tnsping tnsalias

and run lsnrctl services and see if any connection(s) are refused

If oracle client is installed on client machine (from where you are accessing oracle em express)

Run from command prompt:

• ping ipaddress (db host ipaddress) -->> if you get error add IP address and domain name to hosts file

• tnsping tnsalias

Edit:

Dispatcher D000 shows 21 connections refused. You have a network issue.

Try to restart listener and connect to em express and see the lsnrctl services output. Ideally refused connections number should be zero.

StackExchange Database Administrators Q#122807, answer score: 2