diff --git a/packages/react-devtools-shared/src/__tests__/utils-test.js b/packages/react-devtools-shared/src/__tests__/utils-test.js
index dcffd2a228b..9b9e82102cc 100644
--- a/packages/react-devtools-shared/src/__tests__/utils-test.js
+++ b/packages/react-devtools-shared/src/__tests__/utils-test.js
@@ -421,6 +421,26 @@ function f() { }
       await expect(run('http://test/c.mjs')).resolves.toStrictEqual(result);
       await expect(run('http://test/d.mjs')).resolves.toStrictEqual(result);
     });
+
+    it('should not throw for invalid base URL with relative source map', async () => {
+      const fs2 = {
+        'bundle.js': `${source}bundle.js.map`,
+      };
+      const fetch2 = async url => fs2[url] || null;
+      const run = url => symbolicateSource(fetch2, url, 1, 1);
+      await expect(run('bundle.js')).resolves.toBe(null);
+    });
+
+    it('should resolve absolute source map even if base URL is invalid', async () => {
+      const fs3 = {
+        'invalid-base.js': `${source}http://test/a.mjs.map`,
+        'http://test/a.mts': `export function f() {}`,
+        'http://test/a.mjs.map': `{"version":3,"file":"a.mjs","sourceRoot":"","sources":["a.mts"],"names":[],"mappings":";;AAAA,cAAsB;AAAtB,SAAgB,CAAC,KAAI,CAAC"}`,
+      };
+      const fetch3 = async url => fs3[url] || null;
+      const run = url => symbolicateSource(fetch3, url, 4, 10);
+      await expect(run('invalid-base.js')).resolves.toStrictEqual(result);
+    });
   });
 
   describe('formatConsoleArguments', () => {
diff --git a/packages/react-devtools-shared/src/symbolicateSource.js b/packages/react-devtools-shared/src/symbolicateSource.js
index 267e291e120..092b1f8187a 100644
--- a/packages/react-devtools-shared/src/symbolicateSource.js
+++ b/packages/react-devtools-shared/src/symbolicateSource.js
@@ -75,7 +75,18 @@ export async function symbolicateSource(
         resourceLine.length,
       );
 
-      const sourceMapURL = new URL(sourceMapAt, sourceURL).toString();
+      // Compute the absolute source map URL. If the base URL is invalid, gracefully bail.
+      let sourceMapURL;
+      try {
+        sourceMapURL = new URL(sourceMapAt, sourceURL).toString();
+      } catch (e) {
+        // Fallback: try if sourceMapAt is already an absolute URL; otherwise give up.
+        try {
+          sourceMapURL = new URL(sourceMapAt).toString();
+        } catch (_e) {
+          return null;
+        }
+      }
       const sourceMap = await fetchFileWithCaching(sourceMapURL).catch(
         () => null,
       );