View feed or create graph shows error "Request error null"

When trying to view feed data from feeds page I’m redirected to graph page which shows error “Request error null” and no data.

Since yesterday the graphs did not shown any data. I deleted them and tried to create new graphs.
When selecting a feed for graph the error “Request error null” appears

My user is “sey”.
Any idea how to sole the issues?

Thank you,

A post was merged into an existing topic: feed returns NULL