Please run scilab with full debugging enabled and paste (or attach) the full output in this bug. In order to do so, run the following command in a terminal:
$ bash -x /usr/bin/scilab
Also, I noticed that your original report mentioned that you linked default-java to java-8-oracle. This should not be necessary as you have default-jre-headless installed and it should have created the /usr/lib/jvm/default-java by itself. So please check that /usr/lib/jvm/default-java is correctly linked to openjdk-11 directory - if it is not, please remove the manually created link and reinstall the default-jre-headless package.
$ ls -l /usr/lib/jvm/default-java
/usr/lib/jvm/default-java -> java-1.11.0-openjdk-amd64
Please run scilab with full debugging enabled and paste (or attach) the full output in this bug. In order to do so, run the following command in a terminal:
$ bash -x /usr/bin/scilab
Also, I noticed that your original report mentioned that you linked default-java to java-8-oracle. This should not be necessary as you have default- jre-headless installed and it should have created the /usr/lib/ jvm/default- java by itself. So please check that /usr/lib/ jvm/default- java is correctly linked to openjdk-11 directory - if it is not, please remove the manually created link and reinstall the default- jre-headless package.
$ ls -l /usr/lib/ jvm/default- java jvm/default- java -> java-1. 11.0-openjdk- amd64
/usr/lib/
And it should belong to default- jre-headless:
$ dpkg -S /usr/lib/ jvm/default- java jre-headless: /usr/lib/ jvm/default- java
default-