We do see this error appears less frequently with recent updates being rolled out, but sometimes the catching screen gets stuck due to bugs. This takes considerable time of the users till app gets responsive again.

There is no way other than to restart the app. Otherwise, you can also wait for a while for the screen to respond.

So what happens, instead your screen shows what you have just caught, it will present it already appearing on your Pokémon List. Plus it will also become visible on Pokedex, is it’s a Pokémon you have not seen and caught before.

If you face Pokémon catching getting stuck very often when the app crash, do give it some time before actually restarting the app.