diff --git a/packages/theme/src/components/BlogAuthor.vue b/packages/theme/src/components/BlogAuthor.vue
index 37308220..83885f5e 100644
--- a/packages/theme/src/components/BlogAuthor.vue
+++ b/packages/theme/src/components/BlogAuthor.vue
@@ -12,10 +12,11 @@ const author = computed(() =>
   ?? site.value.themeConfig?.blog?.author
 )
 const logo = computed(() =>
-  frontmatter.value.logo
+  frontmatter.value?.logo
   ?? frontmatter.value?.blog?.logo
   ?? home?.logo
-  ?? site.value.themeConfig.logo
+  ?? site.value?.themeConfig?.logo
+  ?? '/logo.png'
 )
 const show = computed(() => author.value || logo.value)
 </script>
diff --git a/packages/theme/src/components/BlogHomeHeaderAvatar.vue b/packages/theme/src/components/BlogHomeHeaderAvatar.vue
index e072e4b4..5452e448 100644
--- a/packages/theme/src/components/BlogHomeHeaderAvatar.vue
+++ b/packages/theme/src/components/BlogHomeHeaderAvatar.vue
@@ -9,7 +9,8 @@ const logo = computed(() =>
   frontmatter.value.logo
     ?? frontmatter.value?.blog?.logo
     ?? home?.logo
-    ?? site.value.themeConfig.logo
+    ?? site.value.themeConfig?.logo
+    ?? '/logo.png'
 )
 const alwaysHide = computed(() => frontmatter.value.blog?.minScreenAvatar === false)
 </script>