diff --git a/packages/block-editor/src/components/block-list/block.js b/packages/block-editor/src/components/block-list/block.js
index 6daf20e4757ce..5767ff2df34f0 100644
--- a/packages/block-editor/src/components/block-list/block.js
+++ b/packages/block-editor/src/components/block-list/block.js
@@ -15,8 +15,8 @@ import {
 } from '@wordpress/element';
 import {
 	getBlockType,
-	getSaveContent,
 	isUnmodifiedDefaultBlock,
+	serializeRawBlock,
 } from '@wordpress/blocks';
 import { withFilters } from '@wordpress/components';
 import {
@@ -74,6 +74,7 @@ function Block( { children, isHtml, ...props } ) {
 }
 
 function BlockListBlock( {
+	block: { source },
 	mode,
 	isLocked,
 	canRemove,
@@ -155,7 +156,7 @@ function BlockListBlock( {
 	let block;
 
 	if ( ! isValid ) {
-		const saveContent = getSaveContent( blockType, attributes );
+		const saveContent = serializeRawBlock( source );
 
 		block = (
 			<Block className="has-warning">
diff --git a/packages/blocks/README.md b/packages/blocks/README.md
index ed08426aa52bc..d87e547f2df8a 100644
--- a/packages/blocks/README.md
+++ b/packages/blocks/README.md
@@ -735,6 +735,31 @@ _Returns_
 
 -   `string`: The post content.
 
+### serializeRawBlock
+
+Serializes a block node into the native HTML-comment-powered block format.
+CAVEAT: This function is intended for reserializing blocks as parsed by
+valid parsers and skips any validation steps. This is NOT a generic
+serialization function for in-memory blocks. For most purposes, see the
+following functions available in the `@wordpress/blocks` package:
+
+_Related_
+
+-   serializeBlock
+-   serialize For more on the format of block nodes as returned by valid parsers:
+-   `@wordpress/block-serialization-default-parser` package
+-   `@wordpress/block-serialization-spec-parser` package
+
+_Parameters_
+
+-   _rawBlock_ `import(".").WPRawBlock`: A block node as returned by a valid parser.
+-   _options_ `?Object`: Serialization options.
+-   _options.isCommentDelimited_ `?boolean`: Whether to output HTML comments around blocks.
+
+_Returns_
+
+-   `string`: An HTML string representing a block.
+
 ### setCategories
 
 Sets the block categories.
diff --git a/packages/blocks/src/api/index.js b/packages/blocks/src/api/index.js
index b5ae50093233d..c179bd2da0236 100644
--- a/packages/blocks/src/api/index.js
+++ b/packages/blocks/src/api/index.js
@@ -34,6 +34,7 @@ export {
 // components whose mechanisms can be shielded from the `edit` implementation
 // and just passed along.
 export { default as parse } from './parser';
+export { serializeRawBlock } from './parser/serialize-raw-block';
 export {
 	getBlockAttributes,
 	parseWithAttributeSchema,
diff --git a/packages/blocks/src/api/parser/index.js b/packages/blocks/src/api/parser/index.js
index 38c21482b5a23..f73133a48170a 100644
--- a/packages/blocks/src/api/parser/index.js
+++ b/packages/blocks/src/api/parser/index.js
@@ -41,12 +41,13 @@ import { applyBuiltInValidationFixes } from './apply-built-in-validation-fixes';
  *
  * @typedef WPBlock
  *
- * @property {string}    name             Block name
- * @property {Object }   attributes       Block raw or comment attributes.
- * @property {WPBlock[]} innerBlocks      Inner Blocks.
- * @property {string}    originalContent  Original content of the block before validation fixes.
- * @property {boolean}   isValid          Whether the block is valid.
- * @property {Object[]}  validationIssues Validation issues.
+ * @property {string}     name             Block name
+ * @property {Object }    attributes       Block raw or comment attributes.
+ * @property {WPBlock[]}  innerBlocks      Inner Blocks.
+ * @property {string}     originalContent  Original content of the block before validation fixes.
+ * @property {boolean}    isValid          Whether the block is valid.
+ * @property {Object[]}   validationIssues Validation issues.
+ * @property {WPRawBlock} [source]         Un-processed original copy of block if created through parser.
  */
 
 /**
@@ -242,6 +243,13 @@ export function parseRawBlock( rawBlock ) {
 		blockType
 	);
 
+	if ( ! updatedBlock.isValid ) {
+		// Preserve the original unprocessed version of the block
+		// that we received so that we can preserve it in its
+		// existing state when we save.
+		updatedBlock.source = rawBlock;
+	}
+
 	if ( ! validatedBlock.isValid && updatedBlock.isValid ) {
 		/* eslint-disable no-console */
 		console.groupCollapsed( 'Updated Block: %s', blockType.name );