msfp is not defined

Hi,
Since last update, I ve an js error when I want to add a step :

msf-backend.min.js?ver=1.5.1:1 Uncaught ReferenceError: msfp is not defined
at g (msf-backend.min.js?ver=1.5.1:1)
at HTMLAnchorElement.<anonymous> (msf-backend.min.js?ver=1.5.1:1)
at HTMLAnchorElement.dispatch (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,moxiejs,plupload,jquery-ui-core,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable&ver=5.1.1:3)
at HTMLAnchorElement.r.handle (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,moxiejs,plupload,jquery-ui-core,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable&ver=5.1.1:3)

I tried with Firefox and Chrome, and I ve the same error. No way to add a step. Could you help me ?
Thank you

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