diff --git a/docusaurus.config.ts b/docusaurus.config.ts
index 078172863716b117268405077ca7bcd1abe54708..3898f01c5118505eac0afe965c47f4200efc55a9 100644
--- a/docusaurus.config.ts
+++ b/docusaurus.config.ts
@@ -3,7 +3,7 @@ import type {Config} from '@docusaurus/types';
 import type * as Preset from '@docusaurus/preset-classic';
 
 const branchName = process.env.CI_COMMIT_REF_NAME || 'main'; // Default to 'main' if undefined
-const branchSuffix = branchName.match(/^instances\/(.*)$/)[1];
+const branchSuffix = branchName.match(/^instances\/(.*)$/)?.[1] || 'main';
 const url = branchName === 'main' ? '/intro2sc-handson' :`/intro2sc-handson/${branchSuffix}/`; // Adjust as needed