Unable to open/connect to Oracle 12c Enterprise Manager Express
I had the same problem after installing Oracle 12.2.0.1 on Windows 2016 without ASM and without RAC.

First I found that TCP/IPv6 was on so I turned it off.

Then tried following Oracle Note Number (Doc ID 1608258.1) - 12c EM Express shows Invalid Certificate Error in web browser.

Also didn't work.

I fixed it by old school way ... :)

I discovered that the Windows user Oracle_DBA (that logged on the PC and used to install Oracle 12c) don't have any permissions on the 2 files under the folder "xdb_wallet".

So:

1- I changed the ownership for the folder "xdb_wallet" from whatever it was to Oracle_DBA :

 

2- changed the ownership of the 2 files ( ewallet.p12 , cwallet.sso ) under the folder "xdb_wallet" from whatever it was to Oracle_DBA :



3- I did step 1 again , and checked that ownership changed for the 2 file.

The website   https://hostname:5500/em   worked fine on FireFox , because IE11/Win2016 has funny issues with Flash Player.

I don't know from security point of view what that means (steps 1-3), or what threats might happens due to those changes.

Please advice if you know.