diff --git a/packages/core/src/internal/bolt-agent/browser/bolt-agent.ts b/packages/core/src/internal/bolt-agent/browser/bolt-agent.ts
index ae29b1048..f31dcec51 100644
--- a/packages/core/src/internal/bolt-agent/browser/bolt-agent.ts
+++ b/packages/core/src/internal/bolt-agent/browser/bolt-agent.ts
@@ -35,8 +35,12 @@ export function fromVersion (
   version: string, 
   getSystemInfo: () => SystemInfo = () => ({ 
     get userAgent()  {
+      // this should be defined as an `var` since we need to get information
+      // came from the global scope which not always will be defined
+      // and we don't want to override the information
+      var navigator
       // @ts-ignore: browser code so must be skipped by ts
-      return window.navigator.userAgent
+      return navigator?.userAgent
     } 
   })
 ): BoltAgent {
diff --git a/packages/core/test/internal/bolt-agent/browser/bolt-agent.test.ts b/packages/core/test/internal/bolt-agent/browser/bolt-agent.test.ts
index 4f882ae75..3ad87b033 100644
--- a/packages/core/test/internal/bolt-agent/browser/bolt-agent.test.ts
+++ b/packages/core/test/internal/bolt-agent/browser/bolt-agent.test.ts
@@ -66,4 +66,14 @@ describe('#unit boltAgent', () => {
       product: 'neo4j-javascript/5.3'
     })
   })
+
+  it('should handle navigator object does not exist in the default getSystemInfo', () => {
+    const version = '5.3'
+
+    const boltAgent = fromVersion(version)
+
+    expect(boltAgent).toEqual({
+      product: 'neo4j-javascript/5.3'
+    })
+  })
 })
diff --git a/packages/neo4j-driver-deno/lib/core/internal/bolt-agent/browser/bolt-agent.ts b/packages/neo4j-driver-deno/lib/core/internal/bolt-agent/browser/bolt-agent.ts
index ae29b1048..f31dcec51 100644
--- a/packages/neo4j-driver-deno/lib/core/internal/bolt-agent/browser/bolt-agent.ts
+++ b/packages/neo4j-driver-deno/lib/core/internal/bolt-agent/browser/bolt-agent.ts
@@ -35,8 +35,12 @@ export function fromVersion (
   version: string, 
   getSystemInfo: () => SystemInfo = () => ({ 
     get userAgent()  {
+      // this should be defined as an `var` since we need to get information
+      // came from the global scope which not always will be defined
+      // and we don't want to override the information
+      var navigator
       // @ts-ignore: browser code so must be skipped by ts
-      return window.navigator.userAgent
+      return navigator?.userAgent
     } 
   })
 ): BoltAgent {