--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/parser/JavaTokenizer.java	Mon Jul 15 16:25:23 2019 -0700
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/parser/JavaTokenizer.java	Tue Jul 16 10:48:22 2019 +0200
@@ -99,6 +99,10 @@
      */
     protected boolean shouldTranslateEscapes;
 
+    /** Has the string broken escapes?
+     */
+    protected boolean hasBrokenEscapes;
+
     protected ScannerFactory fac;
 
     // The set of lint options currently in effect. It is initialized
@@ -261,6 +265,7 @@
                 case '\\':
                     reader.putChar(true); break;
                 default:
+                    hasBrokenEscapes = true;
                     lexError(reader.bp, Errors.IllegalEscChar);
                 }
             }
@@ -426,6 +431,7 @@
         // Clear flags.
         shouldStripIndent = false;
         shouldTranslateEscapes = false;
+        hasBrokenEscapes = false;
         // Check if text block string methods are present.
         boolean hasTextBlockSupport = TextBlockSupport.hasSupport();
         // Track the end of first line for error recovery.
@@ -1038,7 +1044,7 @@
                         string = TextBlockSupport.stripIndent(string);
                     }
                     // Translate escape sequences if present.
-                    if (shouldTranslateEscapes) {
+                    if (shouldTranslateEscapes && !hasBrokenEscapes) {
                         string = TextBlockSupport.translateEscapes(string);
                     }
                     // Build string token.

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/langtools/tools/javac/TextBlockIllegalEscape.java	Tue Jul 16 10:48:22 2019 +0200
@@ -0,0 +1,14 @@
+/*
+ * @test /nodynamiccopyright/
+ * @bug 8227640
+ * @summary Verify that illegal escapes in text blocks do not crash the javac.
+ * @compile/fail/ref=TextBlockIllegalEscape.out --enable-preview -source ${jdk.version} -XDrawDiagnostics TextBlockIllegalEscape.java
+ */
+
+public class TextBlockIllegalEscape {
+    static void test() {
+        EQ("""
+           \!
+           """, "");
+    }
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/langtools/tools/javac/TextBlockIllegalEscape.out	Tue Jul 16 10:48:22 2019 +0200
@@ -0,0 +1,4 @@
+TextBlockIllegalEscape.java:11:13: compiler.err.illegal.esc.char
+- compiler.note.preview.filename: TextBlockIllegalEscape.java
+- compiler.note.preview.recompile
+1 error