[4.0.5] new installation - draft posts not accepted

My b2evolution Version: 4.0.5

I am a new user of b2evolution and not familiar with php etc.

The following message appears when I write and then try to save a short post.

Not Acceptable

An appropriate representation of the requested resource /blog/admin.php could not be found on this server.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

However when I simply write testing in the header and then testing testing in the main text area it is saved as a draft and appears in the list.

Please suggest solution - probably something simple I have overlooked in a setting- hopefully

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