Summary

 If you have multiple SSH keys configured to access different Bitbucket accounts, you may encounter the below error while performing Git operations like clone, push, etc.

The requested repository either does not exist or you do not have access. If you believe this repository exists and you have access, make sure you're authenticated.
fatal: Could not read from remote repository.

Cause

When multiple keys are added as identities in the ssh-agent when you try to clone a repository from a bitbucket account, Bitbucket.org may get authenticated from one of the keys which are not authorized to access the repositories and the clone will fail with the above error. This is an expected consequence of the SSH protocol. The client auth happens long before any repository information is available, so the Bitbucket cloud accepts the first valid key that is offered. It's up to the client to provide the correct key when connecting, which the below solution ensures.

Solution

Workaround 1:

Use different top-level directories for personal and official work. The gitconfig includes overrides based on what path your repository resides.

Example contents of global .gitconfig at /Users/<username>/.gitconfig

[includeIf "gitdir:~/organization_code/"]
    path = ~/organization_code/.gitconfig

[includeIf "gitdir:~/personal_code/"]
    path = ~/personal_code/.gitconfig

Example contents of ~/organization_code/.gitconfig 

[user]
name = John Smith
email = john.smith@organization.net

[core]
sshCommand = ssh -i ~/.ssh/id_rsa_organization

Example contents of ~/personal_code/.gitconfig


[user]
name = John Smith
email = john.smith@personal.net

[core]
sshCommand = ssh -i ~/.ssh/id_rsa_personal

Workaround 2:

Use host nicknames for your personal and organization SSH keys.

1. For example, 2 keys were placed at:
   

   ~/.ssh/id_rsa_personal 
   ~/.ssh/id_rsa_organization 

2. You can delete all cached keys before

   $ ssh-add -D

3. Then, add these two keys to your SSH agent

   $ ssh-add ~/.ssh/id_rsa_personal
   $ ssh-add ~/.ssh/id_rsa_organization

4. You can check your saved keys by executing the below command

   $ ssh-add -l

5. Modify the ssh config

   $ cd ~/.ssh/
   $ touch config
   $ vi config 
   
   or use your favourite editor

6. Finally, add the ssh configuration as shown below:

   #personal account
   Host bitbucket.org-personal
   	HostName bitbucket.org
   	User git
   	IdentityFile ~/.ssh/id_rsa_personal
   
   #organization account
   Host bitbucket.org-organization
   	HostName bitbucket.org
   	User git
   	IdentityFile ~/.ssh/id_rsa_organization

Here are some examples of how you can use the host nicknames:

For Personal account

git clone git@bitbucket.org-personal:<workspace>/<repo-slug>.git

For Organization account

git clone git@bitbucket.org-organization:<workspace>/<repo-slug>.git

eg:

[remote "origin"]
        url = git@bitbucket.org-personal:<workspace>/<repo-slug>.git