--- a/src/java.base/share/classes/sun/util/locale/provider/CalendarDataUtility.java	Thu Jun 27 10:39:27 2019 +0200
+++ b/src/java.base/share/classes/sun/util/locale/provider/CalendarDataUtility.java	Fri Jun 28 08:48:17 2019 -0700
@@ -249,9 +249,15 @@
             switch (requestID) {
             case FIRST_DAY_OF_WEEK:
                 value = calendarDataProvider.getFirstDayOfWeek(locale);
+                if (value == 0) {
+                    value = MONDAY; // default for the world ("001")
+                }
                 break;
             case MINIMAL_DAYS_IN_FIRST_WEEK:
                 value = calendarDataProvider.getMinimalDaysInFirstWeek(locale);
+                if (value == 0) {
+                    value = 1; // default for the world ("001")
+                }
                 break;
             default:
                 throw new InternalError("invalid requestID: " + requestID);

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/jdk/sun/util/locale/provider/CalendarDataRegression.java	Fri Jun 28 08:48:17 2019 -0700
@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8226876
+ * @summary Test CalendarDataUtility class not throwing AssertionError
+ * @run main/othervm -ea -esa -Djava.locale.providers=HOST CalendarDataRegression
+ */
+
+import java.text.DateFormat;
+import java.util.Locale;
+
+public class CalendarDataRegression {
+    public static void main(String[] args) {
+        // Host locale provider on Windows returns 0 for
+        // firstDayOfWeek/minimalDaysInFirstWeek, which should
+        // default to non-zero value. Otherwise AssertionError
+        // will be thrown.
+        DateFormat.getDateInstance(DateFormat.FULL, Locale.US);
+    }
+}