Hi @atefeh amirpour ,
Welcome to the community!
Check for three things!
1. Make sure the Internet connection is stable!
2. Clear your Trello apps cache!
3. Make sure not to run multiple software at a time! Some times CPU can't take a load of multiple software at the same time and it shows the blank screen of the app/software!
Hello Community! My name is Brittany Joiner and I am a Trello enthusiast and Atlassian Community Leader. I'll be sharing with you a series of videos with my top tips on how to best use Trello...
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