minor #2301 Added exact error message (ThomasLandauer)
minor #2301 Added exact error message (ThomasLandauer)

This PR was submitted for the master branch but it was merged into the 1.x branch instead (closes #2301).

Discussion
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Added exact error message

For search engines

Commits
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80c04d27 Added exact error message

yceruto/EasyAdminBundle,OskarStark/EasyAdminBundle,javiereguiluz/EasyAdminBundle,OskarStark/EasyAdminBundle,yceruto/EasyAdminBundle,javiereguiluz/EasyAdminBundle,OskarStark/EasyAdminBundle,yceruto/EasyAdminBundle