If your encountering #15014 request exception, please read here:
If your encountering login issue, follow the step for self debugging:
0. Be sure this account can login on the phone.
1. Try to use your phone to login same account and see if it's workable.
2. For PTC account, you need to verify your e-mail address, otherwise you can't login after 7 days.
3. For google account, if you enable 2-factor authentication, you can't login. Solution here:
4. For google account, please use <username>@gmail.com to login. Many users forgot to type in @gmail.com as it's required to login on the phone.
5. Be sure Bossland api installed. Due to Niantic updated their server and blocks all legacy access, bossland api becomes mandatory. We will soon add a feature to verify if your bossland api is valid.
6. Check your firewall and anti-virus settings. Try to disable them and see if it works.
7. Check Windows UAC setings, try to disable or check settings. (credit to kombatzero)
8. Try to change your password to remove special character. Currently, some symbol such as "^" is not supported. (credit to TGYates)
9. Open command line (CMD.exe) and input "ipconfig /flushdns". (credit to Krii86a)
10. Check your local time in PC, PTC account needs correct local time to login. (credit to Vivion)
11. Restart computer and try again. (credit to iamking1020)
12. Be sure your java version is up-to-date. https://java.com/en/download/
13. If still fail, create a new account then try again. If new account still fail, PM me your account username/password. So we can debug for you. Remember to provide some screen capture and log as it would be very helpful for debugging.