Error during raid boss catching sequence

Probably this has been asked again but I am frustrated. For a second time, while trying to catch the raid boss,error occurred and kicked me out. I entered again the battle, it tried to divert me in the catching sequence but only a black screen appeared with the loading icon. I closed and opened the app and when I entered battle it directed me to the waiting lobby and when 2 minutes passed, it showed error again and I wasn't able to catch the raid boss anymore. I tried it again 6-7 times but with no success. Any suggestions? This time I lost a Machamp, teh previous time a Tyranitar...