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Troubleshooting Git

Sometimes things don't work the way they should or as you might expect when you're using Git. Here are some tips on troubleshooting and resolving issues with Git.

Debugging

When troubleshooting problems with Git, try these debugging techniques.

Use a custom SSH key for a Git command

GIT_SSH_COMMAND="ssh -i ~/.ssh/gitlabadmin" git <command>

Debug problems with cloning

For Git over SSH:

GIT_SSH_COMMAND="ssh -vvv" git clone <git@url>

For Git over HTTPS:

GIT_TRACE_PACKET=1 GIT_TRACE=2 GIT_CURL_VERBOSE=1 git clone <url>

Debug Git with traces

Git includes a complete set of traces for debugging Git commands, for example:

  • GIT_TRACE_PERFORMANCE=1: enables tracing of performance data, showing how long each particular git invocation takes.
  • GIT_TRACE_SETUP=1: enables tracing of what git is discovering about the repository and environment it's interacting with.
  • GIT_TRACE_PACKET=1: enables packet-level tracing for network operations.

Broken pipe errors on git push

'Broken pipe' errors can occur when attempting to push to a remote repository. When pushing you usually see:

Write failed: Broken pipe
fatal: The remote end hung up unexpectedly

To fix this issue, here are some possible solutions.

Increase the POST buffer size in Git

If you're using Git over HTTP instead of SSH, you can try increasing the POST buffer size in Git configuration.

Example of an error during a clone: fatal: pack has bad object at offset XXXXXXXXX: inflate returned -5

Open a terminal and enter:

git config http.postBuffer 52428800

The value is specified in bytes, so in the above case the buffer size has been set to 50 MB. The default is 1 MB.

Stream 0 was not closed cleanly

If you see this error, it may be caused by a slow internet connection:

RPC failed; curl 92 HTTP/2 stream 0 was not closed cleanly: INTERNAL_ERROR (err 2)

If you use Git over HTTP instead of SSH, try one of these fixes:

  • Increase the POST buffer size in the Git configuration with git config http.postBuffer 52428800.
  • Switch to the HTTP/1.1 protocol with git config http.version HTTP/1.1.

If neither approach fixes the error, you may need a different internet service provider.

Check your SSH configuration

If pushing over SSH, first check your SSH configuration as 'Broken pipe' errors can sometimes be caused by underlying issues with SSH (such as authentication). Make sure that SSH is correctly configured by following the instructions in the SSH troubleshooting documentation.

If you're a GitLab administrator with server access, you can also prevent session timeouts by configuring SSH keep-alive on the client or the server.

NOTE: Configuring both the client and the server is unnecessary.

To configure SSH on the client side:

  • On UNIX, edit ~/.ssh/config (create the file if it doesn't exist) and add or edit:

    Host your-gitlab-instance-url.com
  ServerAliveInterval 60
  ServerAliveCountMax 5

  • On Windows, if you are using PuTTY, go to your session properties, then go to "Connection" and under "Sending of null packets to keep session active", set Seconds between keepalives (0 to turn off) to 60.

To configure SSH on the server side, edit /etc/ssh/sshd_config and add:

ClientAliveInterval 60
ClientAliveCountMax 5

Running a git repack

If 'pack-objects' type errors are also being displayed, you can try to run a git repack before attempting to push to the remote repository again:

git repack
git push

Upgrade your Git client

In case you're running an older version of Git (< 2.9), consider upgrading to >= 2.9 (see Broken pipe when pushing to Git repository).

ssh_exchange_identification error

Users may experience the following error when attempting to push or pull using Git over SSH:

Please make sure you have the correct access rights
and the repository exists.
...
ssh_exchange_identification: read: Connection reset by peer
fatal: Could not read from remote repository.

or

ssh_exchange_identification: Connection closed by remote host
fatal: The remote end hung up unexpectedly

or

kex_exchange_identification: Connection closed by remote host
Connection closed by x.x.x.x port 22

This error usually indicates that SSH daemon's MaxStartups value is throttling SSH connections. This setting specifies the maximum number of concurrent, unauthenticated connections to the SSH daemon. This affects users with proper authentication credentials (SSH keys) because every connection is 'unauthenticated' in the beginning. The default value is 10.

This can be verified by examining the host's sshd logs. For systems in the Debian family, refer to /var/log/auth.log, and for RHEL derivatives, check /var/log/secure for the following errors:

sshd[17242]: error: beginning MaxStartups throttling
sshd[17242]: drop connection #1 from [CLIENT_IP]:52114 on [CLIENT_IP]:22 past MaxStartups

The absence of this error suggests that the SSH daemon is not limiting connections, indicating that the underlying issue may be network-related.

Increase the number of unauthenticated concurrent SSH connections

Increase MaxStartups on the GitLab server by adding or modifying the value in /etc/ssh/sshd_config:

MaxStartups 100:30:200

100:30:200 means up to 100 SSH sessions are allowed without restriction, after which 30% of connections are dropped until reaching an absolute maximum of 200.

After you modify the value of MaxStartups, check for any errors in the configuration.

sudo sshd -t -f /etc/ssh/sshd_config

If the configuration check runs without errors, it should be safe to restart the SSH daemon for the change to take effect.

# Debian/Ubuntu
sudo systemctl restart ssh

# CentOS/RHEL
sudo service sshd restart

Timeout during git push / git pull

If pulling/pushing from/to your repository ends up taking more than 50 seconds, a timeout is issued. It contains a log of the number of operations performed and their respective timings, like the example below:

remote: Running checks for branch: master
remote: Scanning for LFS objects... (153ms)
remote: Calculating new repository size... (cancelled after 729ms)

This could be used to further investigate what operation is performing poorly and provide GitLab with more information on how to improve the service.

Error: Operation timed out

If you encounter an error like this when using Git, it usually indicates a network issue:

ssh: connect to host gitlab.com port 22: Operation timed out
fatal: Could not read from remote repository

To help identify the underlying issue:

  • Connect through a different network (for example, switch from Wi-Fi to cellular data) to rule out local network or firewall issues.
  • Run this bash command to gather traceroute and ping information: mtr -T -P 22 <gitlab_server>.com. To learn about MTR and how to read its output, see the Cloudflare article What is My Traceroute (MTR)?.

git clone over HTTP fails with transfer closed with outstanding read data remaining error

Sometimes, when cloning old or large repositories, the following error is thrown:

error: RPC failed; curl 18 transfer closed with outstanding read data remaining
fatal: The remote end hung up unexpectedly
fatal: early EOF
fatal: index-pack failed

This problem is common in Git itself, due to its inability to handle large files or large quantities of files. Git LFS was created to work around this problem; however, even it has limitations. It's usually due to one of these reasons:

  • The number of files in the repository.
  • The number of revisions in the history.
  • The existence of large files in the repository.

The root causes vary, so multiple potential solutions exist, and you may need to apply more than one:

  • If this error occurs when cloning a large repository, you can decrease the cloning depth to a value of 1. For example:

    variables:
  GIT_DEPTH: 1

  • You can increase the http.postBuffer value in your local Git configuration from the default 1 MB value to a value greater than the repository size. For example, if git clone fails when cloning a 500 MB repository, you should set http.postBuffer to 524288000:

    # Set the http.postBuffer size, in bytes
git config http.postBuffer 524288000

  • You can increase the http.postBuffer on the server side:

    1. Modify the GitLab instance's gitlab.rb file:

      gitaly['configuration'] = {
  # ...
  git: {
    # ...
    config: [
      # Set the http.postBuffer size, in bytes
      {key: "http.postBuffer", value: "524288000"},
    ],
  },
}

    2. After applying this change, apply the configuration change:

      sudo gitlab-ctl reconfigure

For example, if a repository has a very long history and no large files, changing the depth should fix the problem. However, if a repository has very large files, even a depth of 1 may be too large, thus requiring the postBuffer change. If you increase your local postBuffer but the NGINX value on the backend is still too small, the error persists.

Modifying the server is not always an option, and introduces more potential risk. Attempt local changes first.

Password expired error on Git fetch via SSH for LDAP user

If git fetch returns this HTTP 403 Forbidden error on a self-managed instance of GitLab, the password expiration date (users.password_expires_at) for this user in the GitLab database is a date in the past:

Your password expired. Please access GitLab from a web browser to update your password.

Requests made with a SSO account and where password_expires_at is not null return this error:

"403 Forbidden - Your password expired. Please access GitLab from a web browser to update your password."

To resolve this issue, you can update the password expiration by either:

  • Using the gitlab-rails console:

    gitlab-rails console
user.update!(password_expires_at: nil)

  • Using gitlab-psql:

    # gitlab-psql
UPDATE users SET password_expires_at = null WHERE username='<USERNAME>';

The bug was reported in this issue.

Error on Git fetch: "HTTP Basic: Access Denied"

If you receive an HTTP Basic: Access denied error when using Git over HTTP(S), refer to the two-factor authentication troubleshooting guide.

401 errors logged during successful git clone

When cloning a repository via HTTP, the production_json.log file may show an initial status of 401 (unauthorized), quickly followed by a 200.

{
   "method":"GET",
   "path":"/group/project.git/info/refs",
   "format":"*/*",
   "controller":"Repositories::GitHttpController",
   "action":"info_refs",
   "status":401,
   "time":"2023-04-18T22:55:15.371Z",
   "remote_ip":"x.x.x.x",
   "ua":"git/2.39.2",
   "correlation_id":"01GYB98MBM28T981DJDGAD98WZ",
   "duration_s":0.03585
}
{
   "method":"GET",
   "path":"/group/project.git/info/refs",
   "format":"*/*",
   "controller":"Repositories::GitHttpController",
   "action":"info_refs",
   "status":200,
   "time":"2023-04-18T22:55:15.714Z",
   "remote_ip":"x.x.x.x",
   "user_id":1,
   "username":"root",
   "ua":"git/2.39.2",
   "correlation_id":"01GYB98MJ0CA3G9K8WDH7HWMQX",
   "duration_s":0.17111
}

You should expect this initial 401 log entry for each Git operation performed over HTTP, due to how HTTP Basic authentication works.

When the Git client initiates a clone, the initial request sent to GitLab does not provide any authentication details. GitLab returns a 401 Unauthorized result for that request. A few milliseconds later, the Git client sends a follow-up request containing authentication details. This second request should succeed, and result in a 200 OK log entry.

If a 401 log entry lacks a corresponding 200 log entry, the Git client is likely using either:

  • An incorrect password.
  • An expired or revoked token.

If not rectified, you could encounter 403 (Forbidden) errors instead.

403 error when performing Git operations over HTTP

When performing Git operations over HTTP, a 403 (Forbidden) error indicates that your IP address has been blocked by the failed-authentication ban:

fatal: unable to access 'https://gitlab.com/group/project.git/': The requested URL returned error: 403

The 403 can be seen in the production_json.log:

{
   "method":"GET",
   "path":"/group/project.git/info/refs",
   "format":"*/*",
   "controller":"Repositories::GitHttpController",
   "action":"info_refs",
   "status":403,
   "time":"2023-04-19T22:14:25.894Z",
   "remote_ip":"x.x.x.x",
   "user_id":1,
   "username":"root",
   "ua":"git/2.39.2",
   "correlation_id":"01GYDSAKAN2SPZPAMJNRWW5H8S",
   "duration_s":0.00875
}

If your IP address has been blocked, a corresponding log entry exists in the auth_json.log:

{
    "severity":"ERROR",
    "time":"2023-04-19T22:14:25.893Z",
    "correlation_id":"01GYDSAKAN2SPZPAMJNRWW5H8S",
    "message":"Rack_Attack",
    "env":"blocklist",
    "remote_ip":"x.x.x.x",
    "request_method":"GET",
    "path":"/group/project.git/info/refs?service=git-upload-pack"}

The failed authentication ban limits differ depending if you are using a self-managed instance or GitLab.com.