Where are you seeing this message please?
It may well need cleaning up but it does suggest you are running your site with php warnings set to be displayed and if that is the case you are likely to get a lot of them from various plugins etc. This is really not recommended.

Actually this is to do with your blog linking options. There are no ‘types’ enabled (i.e., ‘post’, ‘page’ etc). if you set one of those on then this warning will go away. We did have a small number of upgrades where this failed to be set as it should have been.

Yellow Swordfish said
Where are you seeing this message please?
It may well need cleaning up but it does suggest you are running your site with php warnings set to be displayed and if that is the case you are likely to get a lot of them from various plugins etc. This is really not recommended.

Actually this is to do with your blog linking options. There are no ‘types’ enabled (i.e., ‘post’, ‘page’ etc). if you set one of those on then this warning will go away. We did have a small number of upgrades where this failed to be set as it should have been.

how can i set “php warnings” not to display?

Please noted that I’ve no knowledge about programming. And it’s a bit too difficult for me to understand your explanation sometimes.

Many thanks for your help

You would have to ask your host to suppress warnings. It really is not a good idea to have them displayed but it is not something you can really do yourself unless you self-host of course.

Bit making sure that one of the post-types is checked on on the blog linking options in admin will remove that particular warning.

Got you, thanks

np. glad we could help.