Hi @yrmallu 
I removed composer.lock and vendor and installed composer freshly but still getting the same error.
The error is coming on$auth0->exchange()
The error still being the one you posted above about the GuzzleHttp issue, correct?
That makes sense since exchange() opens and establishes a network connection, but we don’t include any hard dependencies, so Guzzle isn’t coming from our end. The SDK will use whatever is available within your project.
Can you share the contents of your composer.json here? Maybe we can spot something amiss there.