hi

I often have this excecption in my debug log

 {4167142:Mon, 12 Oct 2020 07:39:13 GMT}

EXCEPTION (0): Call to a member function real_escape_string() on bool in .../zenphoto/zp-core/functions-db-MySQLi.php on line 157 

an idea where it might come from ?

Looking at the function that results from the db connection not being setup and therefore the object withn a global variable for it not being available. Nevertheless a method of this object is called. It is from the db_quote() function. This should not be possible to happen within proper Zp environment.

I have not seen this. Perhaps some off usage in a plugin or your theme perhaps? You need to find a way to reproduce this when this happens.