If you have purchased an SSL certificate from a certificate authority (e.g., Comodo, DigiCert, Sectigo) or have an existing certificate, you can install it in Plesk. This is useful for Organization Validated (OV) or Extended Validation (EV) certificates, or when migrating a certificate from another server.

### Before You Begin

- You need the following files from your certificate authority:
  - **SSL certificate** (yourdomain.crt or .pem)
  - **CA bundle** or intermediate certificates (if provided)
  - **Private key** (generated during the CSR process)
- If you do not have a private key, you cannot install the certificate. The private key must match the certificate.

### Uploading the Certificate

1. Log in to **Plesk**.
2. Go to **Websites & Domains** → click your domain.
3. Under **Security**, click **SSL/TLS Certificates**.
4. Click **Add SSL/TLS Certificate**.
5. Select **Upload the certificate files**.
6. Upload the following:
   - **Certificate:** Your domain certificate file.
   - **CA certificate:** The intermediate/bundle certificate (if provided).
   - **Private key:** The private key file.
7. Click **OK** to upload and install the certificate.

### Alternative: Paste Certificate Text

If you have the certificate content as text instead of files:

1. Click **Add SSL/TLS Certificate**.
2. Select **Enter the certificate text**.
3. Paste the certificate, CA bundle, and private key into the respective fields.
4. Click **OK**.

### Assigning the Certificate to Your Domain

1. Go to **Websites & Domains** → click your domain → **Hosting Settings**.
2. Ensure **SSL/TLS support** is checked.
3. From the **Certificate** dropdown, select your uploaded certificate.
4. Click **OK**.

### Important Notes

- The private key must match the certificate. If they do not match, the certificate will not work.
- Custom certificates are not automatically renewed. You must renew and replace them manually before they expire.
- Check the certificate expiry date in **SSL/TLS Certificates** to monitor renewal dates.

### Troubleshooting

**"Unable to install certificate" error:**

- Verify the private key matches the certificate.
- Ensure the certificate text includes the full `BEGIN` and `END` markers.
- Check that the CA bundle is correctly pasted (all intermediate certificates).

**Browser shows "Not Secure" after installing:**

- Ensure the certificate is assigned to the domain in **Hosting Settings**.
- Clear your browser cache and reload.

### Related Guides

- [Generate the CSR first](/hc/help/en/articles/how-to-generate-a-csr-certificate-signing-request-in-plesk)
- [Or use free Let's Encrypt](/hc/help/en/articles/how-to-install-a-free-let-s-encrypt-ssl-in-plesk)
- [Reissue a certificate](/hc/help/en/articles/how-to-reissue-and-replace-an-ssl-certificate-in-plesk)