<#<Hash::DisallowedType: Disallowed type attribute: "yaml">>.
The issues is caused by fix for CVE-2013-0156. Upstream simply dropped the offending test case: https://github.com/rails/rails/commit/e134e171c201e136ce28dc229cdc61944dc59cf2
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.