This means the apt system is broken on your host machine. If you open a terminal window, and run “sudo apt-get update && sudo apt-get check” command, it will fail. SDK Manager requires the command to succeed before installation.
The error is caused by the following line in your /etc/apt/resources.list* file:
Hi kayccc,
Thank you for your answer. Actually it was not broken since I was able to run the command. I just ignored the message and processed with the installation, it worked.
Same problem, same solution. The SDK manager times-out in this check, although I can run (sudo -S apt-get update && sudo -S apt-get check) just fine. So I just skipped the step.