Changing language causes "This URL can only be invoked using POST"

• Type: Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: 6.1.20 EE GA2, 7.0.0 M3
• Fix Version/s: 6.1.X EE, 6.2.2 CE GA3 , 6.2.X EE, 7.0.0 M1
• Component/s: Content Display Widgets > Language widget
• Labels:
  • ee-ts
  • liferay-fixpack-platform-15-6210
• Branch Version/s:
  6.2.x, 6.1.x
• Backported to Branch:
  Committed
• Story Points: 4
• Fix Priority: 3
• Git Pull Request: https://github.com/brianchandotcom/liferay-portal/pull/15984

If a portlet shows an error message and user changes language with language portlet, portlet show "... is temporary unavailable" (in the selected language) and there is a "This URL can only be invoked using POST" warning and PrincipalException in the logs.

steps to reproduce

1. start vanilla Liferay (trunk)
2. add language portlet
3. add Documents and Media portlet
4. add a new folder with Document and Media portlet, named "test"
5. try to add a second folder with the same name ("test")
6. portlet shows and error
7. change language
8. WARN and ERROR in log, Documents and Media portlet says: "Documents and Media est temporairement indisponible." (or similar message in other language)