diff --git a/app/src/components/composer-editor/conversion.tsx b/app/src/components/composer-editor/conversion.tsx
index afdc40255..90b900801 100644
--- a/app/src/components/composer-editor/conversion.tsx
+++ b/app/src/components/composer-editor/conversion.tsx
@@ -405,3 +405,27 @@ export function convertToPlainText(value: Value) {
   };
   return serializeNode(value.document);
 }
+
+/* This is a utility method that converts the value to JSON and strips every node
+of it's sensitive bigts, replacing text, links, images, etc. with "XXX" characers
+of the same length. This allows us to log exceptions with the document's structure
+so we can debug challenging problems but not leak PII. */
+export function convertToShapeWithoutContent(value: Value) {
+  // Sidenote: this uses JSON.stringify to "walk" every key-value pair
+  // in the entire JSON tree and have the opportunity to replace the values.
+  let json: object = { error: 'toJSON failed' };
+  try {
+    json = value.toJSON();
+  } catch (err) {
+    // pass
+  }
+  return JSON.stringify(json, (key, value) => {
+    if (
+      typeof value === 'string' &&
+      ['text', 'href', 'html', 'contentId', 'className'].includes(key)
+    ) {
+      return 'X'.repeat(value.length);
+    }
+    return value;
+  });
+}
diff --git a/app/src/flux/stores/draft-editing-session.ts b/app/src/flux/stores/draft-editing-session.ts
index bd6670510..f59ea0e09 100644
--- a/app/src/flux/stores/draft-editing-session.ts
+++ b/app/src/flux/stores/draft-editing-session.ts
@@ -20,7 +20,7 @@ import { SyncbackDraftTask } from '../tasks/syncback-draft-task';
 
 export type MessageWithEditorState = Message & { bodyEditorState: any };
 
-const { convertFromHTML, convertToHTML } = Conversion;
+const { convertFromHTML, convertToHTML, convertToShapeWithoutContent } = Conversion;
 const MetadataChangePrefix = 'metadata.';
 let DraftStore = null;
 
@@ -44,19 +44,37 @@ function hotwireDraftBodyState(draft: any, session: DraftEditingSession): Messag
       _bodyHTMLValue = inHTML;
 
       if (session._mountedEditor) {
-        // compute it now and apply it, preserving the document history
-        _bodyEditorValue = session._mountedEditor
-          .moveToRangeOfDocument()
-          .delete()
-          .insertFragment(convertFromHTML(inHTML).document)
-          .moveToRangeOfDocument()
-          .moveToStart().value;
+        const inHTMLEditorValue = convertFromHTML(inHTML);
+        try {
+          // try to apply the new value to the existing document to preserve undo history.
+          _bodyEditorValue = session._mountedEditor
+            .moveToRangeOfDocument()
+            .delete()
+            .insertFragment(inHTMLEditorValue.document)
+            .moveToRangeOfDocument()
+            .moveToStart().value;
 
-        // occasionally inserting the new document adds a new line at the beginning of the value.
-        // It's unclaer why this happens...
-        const firstBlock = _bodyEditorValue.document.getBlocks().first();
-        if (firstBlock.text === '') {
-          _bodyEditorValue = session._mountedEditor.removeNodeByKey(firstBlock.key).value;
+          // occasionally inserting the new document adds a new line at the beginning of the value.
+          // It's unclaer why this happens...
+          const firstBlock = _bodyEditorValue.document.getBlocks().first();
+          if (firstBlock.text === '') {
+            _bodyEditorValue = session._mountedEditor.removeNodeByKey(firstBlock.key).value;
+          }
+        } catch (err) {
+          // deleting and re-inserting the whole document seems to push Slate pretty hard and it
+          // sometimes fails with odd schema issues (undefined node, invalid range.) Just fall
+          // back to blowing away undo rather than getting the editor stuck.
+
+          // These errors are "downstream" from the actual problem (an invalid document model).
+          // To debug this, we convert the doc to JSON and replace all the actual text / html
+          // with "XXXX". Sending this home means we can replay the failing transform with an
+          // equivalent document of the same shape.
+          AppEnv.reportError(new Error(`Unable to insert fragment into existing document.`), {
+            underlyingError: err,
+            existingSlateShape: convertToShapeWithoutContent(session._mountedEditor.value),
+            incomingSlateShape: convertToShapeWithoutContent(inHTMLEditorValue),
+          });
+          _bodyEditorValue = inHTMLEditorValue;
         }
       } else {
         // compute it again when it's asked for