Error grave When the application and placed no google play (Serious error When the application and placed in google play)

Good morning, I'm sorry, I is the first time I post on the forum do not know if I'm doing something wrong, I'm from Brazil and my English is not good I'm using google translator, I am coordinator of a team Technovation and my students have made an application for this competition in the test via qrcode the application functioned normally, but put it available on google play, but when you do dowload phones that have the application installed was the phone being in a black screen with the "interface application has stopped working" and the phone to return to work after doing a hard reset, so even after formatted no earlier versions through qrcode though it was the dowload it stopped working again as much of a solution much appreciate your attention porfavor let me know if you get an answer

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Did you first install the apk file manually on a device and test it before uploading it to Google Play? Did this work?

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