Please file a BZ if you can come up with a reproducible test case for this.

Actually this problem can be reproduced with error 4001 too:
1. Add a host via UI, e.g. test.example.com.
2. Delete the host via CLI.
3. Open the host in the UI, an error dialog will appear.
4. Click Cancel, it will go back to the search page.
5. Add the same host again via UI.
6. Open the host in the UI, the following error message will appear in the page content (not in dialog):

Error: IPA Error 4001

test.example.com: host not found

Clicking Refresh doesn't clear the error.

Another way to reproduce the problem:
1. Open the users page in the UI.
2. Stop the httpd service.
3. Open one of the users, the following error message will appear:

Error: Unknown Error

error

1. Start the httpd service.
2. Click Refresh, it doesn't clear the error.

Stopping slapd service will produce a different error message:

Error: Internal Server Error

Internal Server Error

Ticket has been cloned to Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=803050

master:
- 646a4cc
- 6669212

ipa-2-2:
- 801dddf
- 224e8c3