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Effective in 2026, to align with our trunk stable development model and ensure platform stability for the ecosystem, we will publish source code to AOSP in Q2 and Q4. For building and contributing to AOSP, use android-latest-release. The android-latest-release manifest branch will always reference the most recent release pushed to AOSP. For more information, see Changes to AOSP.
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Troubleshoot and fix sync issues
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This page explains how to troubleshoot and fix issues related to
the repo sync command.
Fix network issues
This section provides several suggestions for fixing network issues that can
cause unsuccessful syncs.
Tip: Resyncing after an error can often fix a sync issue.
Use authentication to avoid quota barriers
To protect the servers against excessive use, each IP address that's used to
access source is associated with a quota.
When sharing an IP address with other users, such as when accessing the source
repositories from beyond a NAT firewall, quotas can trigger for normal
patterns. For example, a quota can trigger when several users sync new clients
from the same IP address, within a short period.
To avoid triggering quotas, you can use authenticated access, which uses a
separate quota for each user, regardless of the IP address.
To enable authenticated access:
Create a password with the password generator.
Run the following command to convert your client to use automatic
authentication (without changing branch):
$ repo init -u https://android.googlesource.com/a/platform/manifest
Note that the /a/ directory prefix triggers automatic authentication.
Configure for proxy use
If you're downloading source from behind a proxy, as is common in some
corporate environments, make sure that you explicitly specify a proxy for Repo
to use by running these commands:
$ export HTTP_PROXY=http://proxy_user_id:proxy_password@proxy_server:proxy_port
$ export HTTPS_PROXY=http://proxy_user_id:proxy_password@proxy_server:proxy_port
Adjust TCP/IP settings to avoid connectivity issues
While it's rare, Linux clients can experience connectivity issues, such as
getting stuck in the middle of downloads while receiving objects. To improve
this issue, adjust the settings of the TCP/IP stack or use nonparallel
connections. You must have root access to modify the TCP setting. To modify the
setting, issue the following commands:
$ sudo sysctl -w net.ipv4.tcp_window_scaling=0
$ repo sync -j1
Use a local mirror to avoid network latency
When using several clients, you can create a local mirror of the entire server
content and sync clients from that mirror without accessing the
network. Follow these instructions to create a local mirror in at
~/aosp-mirror/ and sync clients against that mirror:
Create and sync the mirror:
$ mkdir -p /usr/local/aosp/mirror
$ cd /usr/local/aosp/mirror
$ repo init -u https://android.googlesource.com/mirror/manifest --mirror
These commands create a local mirror in /user/local/aosp/mirror and
initialize the mirror using the --mirror flag with the repo init
command.
Sync the clients from the mirror:
$ mkdir -p /usr/local/aosp/main
$ cd /usr/local/aosp/main
$ repo init -u /usr/local/aosp/mirror/platform/manifest.git -b android-latest-release
$ repo sync
Sync the mirror against the server and
sync the clients against the mirror:
$ cd /usr/local/aosp/mirror
$ repo sync
$ cd /usr/local/aosp/android-latest-release
$ repo sync
It's possible to store the mirror on a LAN server and to access it over NFS,
SSH, or Git. It's also possible to store it on a removable drive and to pass
that drive among users or machines.
Use a partial clone
If you're using Git version 2.19 or later, specify --partial-clone when
performing repo init to overcome any low-latency network issues:
$ repo init -u https://android.googlesource.com/platform/manifest -b android-latest-release --partial-clone --clone-filter=blob:limit=10M
Instead of initializing Repo to download everything, this command downloads Git
objects as they are needed.
Troubleshoot 403 or 500 errors (proxy issues)
The repo init or repo sync commands might fail with either a 403 or 500
error. Most often these errors are related to HTTP proxies struggling to
handle the large data transfers.
While there isn't a specific fix to these errors, using the most recent Python
version and explicitly using repo sync -j1 can sometimes help.
Content and code samples on this page are subject to the licenses described in the Content License. Java and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.
Last updated 2026-06-17 UTC.
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