AEM request forward 500

Question

I have a scenario,

1. Created a sling servlet to be hit in browser.
2. Do some heavy lifting.

3. Set some attributes/parameters in slingRequest

4. Finally used requestDispatcher.forward(slingRequest,singResponse) to redirect to a page.

5. Once landed on page, user slingRequest to get attributes/parameters and use it.

Now when i use it, i see HTTP 500 error in browser without any trace of what bad has happened.

I referred sling docs @ https://sling.apache.org/documentation/the-sling-engine/dispatching-requests.html but no help.

Has anybody faced it ever? Any reason/remedy?