For one of the critical replatforming projects I was part of, we communicated that testing was successful but had not covered the aspect of stress testing. During staging, we realized that the system was slow and needed to have it covered. We came clean, communicated the issue to the project manager and we had the testing team to work overtime so that we could close this gap. We successfully covered this aspect, and the project was a success having sorted issues related to slowness.
