Warning in the server

Could someone help me to understand what is wrong and how to fix it.

Warning: exec(): Unable to fork [/etc/java -jar /usr/share/java/saxon.jar -? 2>&1] in /home/admin/web/domainname.com/public_html/wp-content/plugins/pressbooks/inc/utility/namespace.php on line 372

@johnpeterm I believe that the saxon.jar file is related to the Saxon HE dependency (https://sourceforge.net/projects/saxon/files/Saxon-HE/) used to help produce certain file exports. You may want to check on the installation of that package (see installation instructions here: https://docs.pressbooks.org/installation/).

Thank You @SteelWagstaff.

In the same server, we have two instance of pressbook, while the one works perfectly fine, in the another, the above mentioned error throws up while exporting epup file, while the other export like PDF etc works fine. The above warning comes while exporting epup file.

We have installed necessary add on in the server. It works perfectly for one instance.

We have also followed pressbook installation instructions carefully. Now we are unable to locate where the problem is, The problem is in server or in pressbook.

We haven’t had this problem with any of our hosted networks. The fact that you have it working for one of the two installations makes me think that it’s a server rather than a software issue. Sorry I can’t be of more help. Good luck!