Sourcetree can't pull/push login problems on v3.0.15 and v3.1.2

[Balint Nagy]

I could copy-paste others' problem here:
I was using SourceTree v3.0.15 with BitBucket, then suddenly on a pull or a push it asked for authentication. It displays my account name, I changed that to my email address, entered my password, login failed again. I tried with my account name, I tried changing my password, turning my local firewall off, restarting my machine, upgrading SourceTree to v3.1.2, downgrading to an earlier version (which I couldn't), logging in to id.atlassian.com with a browser, deleting stored passwords from the Windows vault - nothing's working: from this box, I can't push/pull using SourceTree. From a different box, I can push/ pull using an older version and using v3.1.2 (however this one's never asking for a password, even after a change). I can log in to id.atlassian.com.

I also tried deleting the password file mentioned here https://community.atlassian.com/t5/Sourcetree-questions/Sourcetree-can-t-push-login-problems/qaq-p/952536
but I don't have a password file.

I went into SourceTree / Tools / Options / Authentication, opened the account with <myusername@bitbucket.org> / Edit / Refresh OAuth token. Status changed from "Authentication error" to "Authentication OK". Tried Pull again - failed.

Switched to Basic authentication - failed.

Deleted my login information, tried basic and OAuth authentication, HTTPS and SSH channels - all failed. All the while the account information screen shows "Authentication OK".

It'd be fairly urgent, i'm stuck on development...

The box where it doesn't work is Windows 7 Pro, the one where it is working is Windows 10.

The Windows Event Log shows information messages with this content: "Failed to retrieve Bitbucket credentials for 'https://bitbucket.org/'."

There are error messages as well, although they don't seem to coincide with failed pull attempts:
-------------------

System.Net.Http.HttpRequestException: An error occurred while sending the request. ---> System.Net.WebException: The request was aborted: Could not create SSL/TLS secure channel.
at System.Net.HttpWebRequest.EndGetResponse(IAsyncResult asyncResult)
at System.Net.Http.HttpClientHandler.GetResponseCallback(IAsyncResult ar)
--- End of inner exception stack trace ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Atlassian.Bitbucket.Authentication.Rest.RestClient.<TryGetUser>d__3.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Atlassian.Bitbucket.Authentication.Authority.<ValidateCredentials>d__11.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Atlassian.Bitbucket.Authentication.Authority.<ValidateCredentials>d__6.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Atlassian.Bitbucket.Authentication.Authentication.<ValidateCredentials>d__33.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Microsoft.Alm.Cli.CommonFunctions.<>c__DisplayClass9_5.<<QueryCredentials>b__5>d.MoveNext()-------------------

[Balint Nagy]

To work around this, I set up an SSH connection.

See https://confluence.atlassian.com/bitbucket/set-up-an-ssh-key-728138079.html