diff -Nru scilab-6.1.0+dfsg1/debian/changelog scilab-6.1.0+dfsg1/debian/changelog
--- scilab-6.1.0+dfsg1/debian/changelog	2020-03-05 19:48:44.000000000 +0100
+++ scilab-6.1.0+dfsg1/debian/changelog	2021-09-09 10:30:09.000000000 +0200
@@ -1,3 +1,9 @@
+scilab (6.1.0+dfsg1-1ubuntu3.1) focal; urgency=medium
+
+  * d/p/addLibraryPath.patch: fix crash at startup. LP: #1870813
+
+ -- Simon Chopin <simon.chopin@canonical.com>  Thu, 09 Sep 2021 10:30:09 +0200
+
 scilab (6.1.0+dfsg1-1ubuntu3) focal; urgency=medium
 
   * fix ftbfs with new icu
diff -Nru scilab-6.1.0+dfsg1/debian/patches/addLibraryPath.patch scilab-6.1.0+dfsg1/debian/patches/addLibraryPath.patch
--- scilab-6.1.0+dfsg1/debian/patches/addLibraryPath.patch	1970-01-01 01:00:00.000000000 +0100
+++ scilab-6.1.0+dfsg1/debian/patches/addLibraryPath.patch	2021-09-09 10:29:36.000000000 +0200
@@ -0,0 +1,51 @@
+Description: Starting with openjdk 11.0.7+9 it is not possible anymore
+ to force java.library.path reload by setting sys_paths to null.
+ This patch makes things work for both openjdk 11.0.6 and 11.0.7.
+ Related jdk changeset:
+ http://hg.openjdk.java.net/jdk-updates/jdk11u/rev/21710e014d7f
+Author: Gilles Filippini <pini@debian.org>
+Forwarded: http://bugzilla.scilab.org/show_bug.cgi?id=16423
+
+--- scilab.orig/scilab/modules/jvm/src/java/org/scilab/modules/jvm/LibraryPath.java
++++ scilab/scilab/modules/jvm/src/java/org/scilab/modules/jvm/LibraryPath.java
+@@ -19,7 +19,9 @@
+ /*--------------------------------------------------------------------------*/
+ import java.io.IOException;
+ import java.io.File;
++import java.lang.reflect.Method;
+ import java.lang.reflect.Field;
++import java.lang.reflect.InvocationTargetException;
+ /*--------------------------------------------------------------------------*/
+ /*http://forum.java.sun.com/thread.jspa?threadID=135560&start=15&tstart=0 */
+ /*--------------------------------------------------------------------------*/
+@@ -64,14 +66,25 @@
+             /* The order matter here... see bug #4022 */
+             String newLibPath = System.getProperty(JAVALIBRARYPATH) + File.pathSeparator + p;
+             System.setProperty(JAVALIBRARYPATH, newLibPath);
++            // First try the new initLibraryPaths method
+             try {
+-                Field fieldSysPath = ClassLoader.class.getDeclaredField("sys_paths");
+-                fieldSysPath.setAccessible(true);
+-                if (fieldSysPath != null) {
++                final Method initLibraryPaths = ClassLoader.class.getDeclaredMethod("initLibraryPaths");
++                initLibraryPaths.setAccessible(true);
++                initLibraryPaths.invoke(null);
++            } catch (NoSuchMethodException e) {
++                // The initLibraryPaths method doesn't exist
++                // Fallback setting sys_paths to null
++                try {
++                    Field fieldSysPath = ClassLoader.class.getDeclaredField("sys_paths");
++                    fieldSysPath.setAccessible(true);
+                     fieldSysPath.set(System.class.getClassLoader(), null);
++                } catch (NoSuchFieldException e1) {
++                    throw new IOException("Error NoSuchFieldException, could not add path to " + JAVALIBRARYPATH);
++                } catch (IllegalAccessException e1) {
++                    throw new IOException("Error IllegalAccessException, could not add path to " + JAVALIBRARYPATH);
+                 }
+-            } catch (NoSuchFieldException e) {
+-                throw new IOException("Error NoSuchFieldException, could not add path to " + JAVALIBRARYPATH);
++            } catch (InvocationTargetException e) {
++                throw new IOException("Error InvocationTargetException, could not add path to " + JAVALIBRARYPATH);
+             } catch (IllegalAccessException e) {
+                 throw new IOException("Error IllegalAccessException, could not add path to " + JAVALIBRARYPATH);
+             }
diff -Nru scilab-6.1.0+dfsg1/debian/patches/series scilab-6.1.0+dfsg1/debian/patches/series
--- scilab-6.1.0+dfsg1/debian/patches/series	2020-03-05 19:48:44.000000000 +0100
+++ scilab-6.1.0+dfsg1/debian/patches/series	2021-09-09 10:30:09.000000000 +0200
@@ -15,4 +15,5 @@
 ocaml_406.patch
 find_libs.patch
 strange_us_ascii_unmappable_character.patch
+addLibraryPath.patch
 no-ftbfs-icu.patch