diff --git a/aio/tools/transforms/remark-package/services/renderMarkdown.js b/aio/tools/transforms/remark-package/services/renderMarkdown.js
index bb0defe5f2..c68701e119 100644
--- a/aio/tools/transforms/remark-package/services/renderMarkdown.js
+++ b/aio/tools/transforms/remark-package/services/renderMarkdown.js
@@ -91,15 +91,19 @@ module.exports = function renderMarkdown() {
       const openMatch = anyBlockMatcher.exec(value);
       if (openMatch) {
         const blockName = openMatch[1];
-        const fullMatch = matchRecursiveRegExp(value, createOpenMatcher(blockName), createCloseMatcher(blockName))[0];
-        if (silent || !fullMatch) {
-          // either we are not eating (silent) or the match failed
-          return !!fullMatch;
+        try {
+          const fullMatch = matchRecursiveRegExp(value, createOpenMatcher(blockName), createCloseMatcher(blockName))[0];
+          if (silent || !fullMatch) {
+            // either we are not eating (silent) or the match failed
+            return !!fullMatch;
+          }
+          return eat(fullMatch[0])({
+            type: 'html',
+            value: fullMatch[0]
+          });
+        } catch(e) {
+          this.file.fail('Unmatched plain HTML block tag ' + e.message);
         }
-        return eat(fullMatch[0])({
-          type: 'html',
-          value: fullMatch[0]
-        });
       }
     }
   }
@@ -161,30 +165,32 @@ function rgxFindMatchPos(str, left, right, flags) {
   let index, match, start, end;
   let count = 0;
 
-  do {
-    while ((match = bothMatcher.exec(str))) {
-      if (leftMatcher.test(match[0])) {
-        if (!(count++)) {
-          index = bothMatcher.lastIndex;
-          start = index - match[0].length;
-        }
-      } else if (count) {
-        if (!--count) {
-          end = match.index + match[0].length;
-          var obj = {
-            left: {start: start, end: index},
-            match: {start: index, end: match.index},
-            right: {start: match.index, end: end},
-            wholeMatch: {start: start, end: end}
-          };
-          pos.push(obj);
-          if (!global) {
-            return pos;
-          }
+  while ((match = bothMatcher.exec(str))) {
+    if (leftMatcher.test(match[0])) {
+      if (!(count++)) {
+        index = bothMatcher.lastIndex;
+        start = index - match[0].length;
+      }
+    } else if (count) {
+      if (!--count) {
+        end = match.index + match[0].length;
+        var obj = {
+          left: {start: start, end: index},
+          match: {start: index, end: match.index},
+          right: {start: match.index, end: end},
+          wholeMatch: {start: start, end: end}
+        };
+        pos.push(obj);
+        if (!global) {
+          return pos;
         }
       }
     }
-  } while (count && (bothMatcher.lastIndex = index));
+  }
+
+  if (count) {
+    throw new Error(str.slice(start, index));
+  }
 
   return pos;
 }
diff --git a/aio/tools/transforms/remark-package/services/renderMarkdown.spec.js b/aio/tools/transforms/remark-package/services/renderMarkdown.spec.js
index ea4409ac5f..d9afc6c762 100644
--- a/aio/tools/transforms/remark-package/services/renderMarkdown.spec.js
+++ b/aio/tools/transforms/remark-package/services/renderMarkdown.spec.js
@@ -49,6 +49,17 @@ describe('remark: renderMarkdown service', () => {
     expect(output).toEqual('<code-example>\n\n  **abc**\n\n  def\n</code-example>\n<code-tabs><code-pane>\n\n  **abc**\n\n  def\n</code-pane></code-tabs>\n');
   });
 
+  it('should handle recursive tags marked as unformatted', () => {
+    const content = '<code-example>\n\n  <code-example>\n\n  **abc**\n\n  def\n\n</code-example>\n\n</code-example>\n\nhij\n\n<code-example>\n\nklm</code-example>';
+    const output = renderMarkdown(content);
+    expect(output).toEqual('<code-example>\n\n  <code-example>\n\n  **abc**\n\n  def\n\n</code-example>\n\n</code-example>\n<p>hij</p>\n<code-example>\n\nklm</code-example>\n');
+  });
+
+  it('should raise an error if a tag marked as unformatted is not closed', () => {
+    const content = '<code-example path="xxx">\n\n  **abc**\n\n  def\n<code-example>\n\n\n\n  **abc**\n\n  def\n</code-example>';
+    expect(() => renderMarkdown(content)).toThrowError('Unmatched plain HTML block tag <code-example path="xxx">');
+  });
+
   it('should not remove spaces after anchor tags', () => {
     var input =
         'A aa aaa aaaa aaaaa aaaaaa aaaaaaa aaaaaaaa aaaaaaaaa aaaaaaaaaa aaaaaaaaaaa\n' +