Steps to reproduce the issue

When opening the edit view for an article or other things like e.g. tags, a red alert popup with title "Error" and text "An error has occurred." is shown.

When saving a newly created article for the first time, another a red alert popup with title "Error" is shown with following text:

Save failed with the following error: 23502, 7, ERROR: null value in column "introtext" violates not-null
constraint DETAIL: Failing row contains (71, 0, test, test, null, , 0, 2, 2019-07-30 17:49:31, 31, ,
1970-01-01 00:00:00, 0, 0, 1970-01-01 00:00:00, 1970-01-01 00:00:00, 1970-01-01 00:00:00,
{"image_intro":"","float_intro":"","image_intro_alt":"","image_i...,
{"urla":"","urlatext":"","targeta":"","urlb":"","urlbtext":"","t...,
{"article_layout":"","show_title":"","link_titles":"","show_tags..., 1, 0, , , 1, 0,
{"robots":"","author":"","rights":""}, 0, *, ).
An error has occurred.

With an already existing article, the 2nd error does not happen.

On a MySQL database, none of these errors happens, it happens only on PostgreSQL.

Expected result

No errors.

Actual result

See above.

System information (as much as possible)

PHP 7.2
PostgreSQL 10.9

Additional comments

Maybe the cause of both is the same 1 error, or maybe it is 2 different errors.