diff --git a/packages/core/src/config.ts b/packages/core/src/config.ts
index da9412c302..0bfbb2cbb5 100644
--- a/packages/core/src/config.ts
+++ b/packages/core/src/config.ts
@@ -471,7 +471,7 @@ export async function loadConfig({
 
   let configExport: RsbuildConfigExport;
 
-  if (/\.(?:js|mjs|cjs)$/.test(configFilePath) || loader === 'native') {
+  if (loader === 'native' || /\.(?:js|mjs|cjs)$/.test(configFilePath)) {
     try {
       const exportModule = await import(`${configFilePath}?t=${Date.now()}`);
       configExport = exportModule.default ? exportModule.default : exportModule;
diff --git a/packages/core/src/provider/initConfigs.ts b/packages/core/src/provider/initConfigs.ts
index 86a64e42a0..b4c966abac 100644
--- a/packages/core/src/provider/initConfigs.ts
+++ b/packages/core/src/provider/initConfigs.ts
@@ -151,6 +151,14 @@ const initEnvironmentConfigs = (
   };
 };
 
+const validateRsbuildConfig = (config: NormalizedConfig) => {
+  if (config.server.base && !config.server.base.startsWith('/')) {
+    throw new Error(
+      `[rsbuild:config] The "server.base" option should start with a slash, for example: "/base"`,
+    );
+  }
+};
+
 export async function initRsbuildConfig({
   context,
   pluginManager,
@@ -215,6 +223,7 @@ export async function initRsbuildConfig({
 
   await updateEnvironmentContext(context, environments);
   updateContextByNormalizedConfig(context);
+  validateRsbuildConfig(context.normalizedConfig);
 
   return context.normalizedConfig;
 }