diff --git a/backend/open_webui/utils/voice_avatar.py b/backend/open_webui/utils/voice_avatar.py
index c921169726..0d55b11e31 100644
--- a/backend/open_webui/utils/voice_avatar.py
+++ b/backend/open_webui/utils/voice_avatar.py
@@ -96,7 +96,8 @@ def validate_voice_animation(data: bytes) -> None:
         ext = model.get('extensions', {}).get('VRMC_vrm_animation', {})
         bones = ext.get('humanoid', {}).get('humanBones', {})
         nodes = model.get('nodes', [])
-        if ext.get('specVersion') != '1.0' or not bones or not 0 < len(nodes) <= 512:
+        # Match the VRMA loader's compatibility fallback for unversioned exports.
+        if ext.get('specVersion') not in (None, '1.0') or not bones or not 0 < len(nodes) <= 512:
             raise ValueError('Use a VRMA 1.0 humanoid animation.')
         for bone in bones.values():
             if type(bone.get('node')) is not int or not 0 <= bone['node'] < len(nodes):
diff --git a/src/lib/utils/voice-avatar-animation.ts b/src/lib/utils/voice-avatar-animation.ts
index f849ab7006..be063ac481 100644
--- a/src/lib/utils/voice-avatar-animation.ts
+++ b/src/lib/utils/voice-avatar-animation.ts
@@ -29,8 +29,9 @@ export function validateAnimation(data: ArrayBuffer) {
 	const json = JSON.parse(new TextDecoder().decode(new Uint8Array(data, 20, length)));
 	const ext = json.extensions?.VRMC_vrm_animation;
 	const bones = Object.values(ext?.humanoid?.humanBones ?? {}) as { node: number }[];
+	// Match the VRMA loader's compatibility fallback for unversioned exports.
 	if (
-		ext?.specVersion !== '1.0' ||
+		(ext?.specVersion != null && ext.specVersion !== '1.0') ||
 		!bones.length ||
 		!json.nodes?.length ||
 		json.nodes.length > 512 ||