> ## Documentation Index
> Fetch the complete documentation index at: https://docs.dify.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# FAQs

## Deployment Methods

### Install Older Version

Use the `--branch` flag to install a specific version:

```bash theme={null}
git clone https://github.com/langgenius/dify.git --branch 0.15.3
```

The rest of the setup is identical to installing the latest version.

### Install Using ZIP Archive

For network-restricted environments or when git is unavailable:

```bash theme={null}
# Download latest release
wget -O dify.zip "$(curl -s https://api.github.com/repos/langgenius/dify/releases/latest | jq -r '.zipball_url')"
unzip dify.zip && rm dify.zip
```

Alternatively, download the ZIP on another device and transfer it manually.

**To upgrade**:

```bash theme={null}
wget -O dify-latest.zip "$(curl -s https://api.github.com/repos/langgenius/dify/releases/latest | jq -r '.zipball_url')"
unzip dify-latest.zip && rm dify-latest.zip
rsync -a dify-latest/ dify/
rm -rf dify-latest/
cd dify/docker
docker compose pull
docker compose up -d
```

## Backup Procedures

### Create Backup Before Upgrading

Always backup before upgrading to prevent data loss:

```bash theme={null}
cp -r dify "dify.bak.$(date +%Y%m%d%H%M%S)"
```

This creates a timestamped backup for easy restoration.

## Reverse Proxy Setup

### Login Session Drops with Split Frontend and Backend Subdomains

If you have split web and API across subdomains behind a reverse proxy (for example, `app.example.com` for the UI and `api.example.com` for the backend), authentication cookies cannot reach both hosts. Login appears to succeed, but the session is dropped on the next request.

Set both variables in `.env`, then restart Dify:

* **`COOKIE_DOMAIN`**: set to the shared top-level domain (e.g., `example.com`). Leading dots are optional.
* **`NEXT_PUBLIC_COOKIE_DOMAIN`**: set to `1` to enable cross-subdomain cookies on the frontend.

```bash theme={null}
docker compose down
docker compose up -d
```

Cookies cannot cross top-level domains, so the frontend and backend must share the same registrable domain. For full details, see [environment variables](/en/self-host/configuration/environments).