ERR_EMPTY_RESPONSE after comment

Hi,

Since yesterday, when I reply to a comment on my blog (https://un-jardin-bio.com), I am redirected to an error page:
“No data received.
Can not display the webpage because the server sent no data. ERR_EMPTY_RESPONSE. “

However, the comment has been saved
Note that I have the same problem by changing browser.
I disabled all plugins to see if the problem was there, but it changes nothing.

I asked a member of my blog post a comment. He has also an error message:
ReadResponse () failed: The server About did not return a response for this request.

On the server side, they tell me that everything is working properly … and they tested by posting a comment, withou any problem…

So I really do not know how to solve it.
Please help me!