Summary

SSH clone requests failing almost immediately when tried to clone

git clone -v ssh://git@bitbucket.internal:7999/at/atlasts.git

14:52:49.366381 git.c:344 trace: built-in: git 'clone' '-v' 'ssh://git@bitbucket.internal:7999/at/atlasts.git'
Cloning into 'atlasts'...
14:52:49.375286 run-command.c:626 trace: run_command: 'ssh' '-p' '7999' 'git@bitbucket.internal' 'git-upload-pack '\''/at/atlasts.git'\'''
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.

Environment

7.6.4

Diagnosis

• Enable debugging on Bitbucket server
• Check the Bitbucket server logs atlassian-bitbucket.log for the below error

2021-05-14 14:41:32,704 DEBUG [sshd-SshServer[116c3165](port=7999)-nio2-thread-7]  c.a.s.i.s.g.p.ssh.GitSshScmRequest upload-pack was canceled before git could be started

Cause

• Modified values for the SSH related parameters on bitbucket.properties file might cause this issue. 
• Check the bitbucket.properties for any SSH-related customizations.

Solution

Check the bitbucket.properties file for plugin.bitbucket-git.hosting.ssh.buffersize if it's set to a higher value than the default 4096 then that could possibly cause this issue.

The default value for the plugin.bitbucket-git.hosting.ssh.buffersize is 4096 and it defines the buffer size in bytes which is used when marshaling data between the git process and the SSH socket. The default is 4K, with a 1K minimum.

To fix the issue remove the plugin.bitbucket-git.hosting.ssh.buffersize parameter and then restart the Bitbucket service for the updated config to take effect and then try to clone again