Switchover Dataguard under Cloud Control 12c fails

During a switchover test in Enterprise Manager Cloud Control 12c, I got the error:

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Session Information Unavailable

Enterprise Manager is unable to proceed. The most likely cause of this is that database session information could not be retrieved or that EM was unable to process a user-invoked bookmark. Press OK to continue.

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The switchover did not take place, even though under DGMGRL it works fine, and the Verify Configuration in Cloud Control reveals no errors.

This appears to be a stupid bug in IE9. It runs fine under Chrome! See Doc ID 1512567.1 under Oracle Support.

This really makes me ....