diff --git a/inc/admin-layouts.php b/inc/admin-layouts.php
index 246d6a10..07203991 100644
--- a/inc/admin-layouts.php
+++ b/inc/admin-layouts.php
@@ -63,6 +63,17 @@ public function get_directories() {
 		return $directories;
 	}
 
+	/**
+	 * Determines if file has a JSON extension.
+	 *
+	 * @param string $file File path.
+	 * @return bool True if JSON, false otherwise.
+	 */
+	private static function check_file_ext( $file ) {
+		$ext = pathinfo( $file, PATHINFO_EXTENSION );
+		return ! empty( $ext ) && $ext === 'json';
+	}
+
 	/**
 	 * Looks through local folders in the active theme and any others filtered in by theme and plugins, to find JSON
 	 * prebuilt layouts.
@@ -92,20 +103,19 @@ public function get_local_layouts() {
 				}
 
 				foreach ( $files as $file ) {
+					$valid_file_type = false;
 					if ( function_exists( 'mime_content_type' ) ) {
-						// get file mime type
 						$mime_type = mime_content_type( $file );
+						$valid_file_type = strpos( $mime_type, '/json' ) !== false;
 
-						// Valid if text files.
-
-						// Valid if text or json file.
-						$valid_file_type = strpos( $mime_type, '/json' ) || strpos( $mime_type, 'text/' ) > -1;
+						if ( ! $valid_file_type ) {
+							// It could have the wrong MIME type. Check for text/plain, and if it is, check the extension.
+							$valid_file_type = strpos( $mime_type, 'text/plain' ) !== false &&
+								self::check_file_ext( $file );
+						}
 					} else {
-						// If `mime_content_type` isn't available, just check file extension.
-						$ext = pathinfo( $file, PATHINFO_EXTENSION );
-
-						// skip files which don't have a `.json` extension.
-						$valid_file_type = ! empty( $ext ) && $ext === 'json';
+						// Can't check MIME. Check extension.
+						$valid_file_type = self::check_file_ext( $file );
 					}
 
 					if ( ! $valid_file_type ) {
@@ -120,28 +130,29 @@ public function get_local_layouts() {
 						continue;
 					}
 
-					// json decode
-					$panels_data = json_decode( $file_contents, true );
+					$panels_data = $this->decode_panels_data( $file_contents );
 
-					if ( ! empty( $panels_data ) ) {
-						// get file name by stripping out folder path and .json extension
-						$file_name = str_replace( array( $folder . '/', '.json' ), '', $file );
+					if ( empty( $panels_data ) ) {
+						continue;
+					}
 
-						// get name: check for id or name else use filename
-						$panels_data['id'] = sanitize_title_with_dashes( $this->get_layout_id( $panels_data, $file_name ) );
+					// get file name by stripping out folder path and .json extension
+					$file_name = str_replace( array( $folder . '/', '.json' ), '', $file );
 
-						if ( empty( $panels_data['name'] ) ) {
-							$panels_data['name'] = $file_name;
-						}
+					// get name: check for id or name else use filename
+					$panels_data['id'] = sanitize_title_with_dashes( $this->get_layout_id( $panels_data, $file_name ) );
 
-						$panels_data['name'] = sanitize_text_field( $panels_data['name'] );
+					if ( empty( $panels_data['name'] ) ) {
+						$panels_data['name'] = $file_name;
+					}
 
-						// get screenshot: check for screenshot prop else try use image file with same filename.
-						$panels_data['screenshot'] = $this->get_layout_file_screenshot( $panels_data, $folder, $file_name );
+					$panels_data['name'] = sanitize_text_field( $panels_data['name'] );
 
-						// set item on layouts array
-						$layouts[ $panels_data['id'] ] = $panels_data;
-					}
+					// get screenshot: check for screenshot prop else try use image file with same filename.
+					$panels_data['screenshot'] = $this->get_layout_file_screenshot( $panels_data, $folder, $file_name );
+
+					// set item on layouts array
+					$layouts[ $panels_data['id'] ] = $panels_data;
 				}
 			}
 		}
diff --git a/readme.txt b/readme.txt
index 4e1980a7..a5b20577 100644
--- a/readme.txt
+++ b/readme.txt
@@ -121,6 +121,10 @@ SiteOrigin offers a single premium plugin that enhances and extends Page Builder
 
 == Changelog ==
 
+= 2.29.21 – 17 September 2024 =
+* Prebuilt Local Layouts: Resolved a potential error.
+* Prebuilt Local Layouts: Restricted layout files to JSON.
+
 = 2.29.20 – 08 August 2024 =
 * Rank Math: Resolved content analysis issue when multiple blocks in use.