--- title: How do I resolve "ERR_SSL_PROTOCOL_ERROR" with Vercel? description: Information about how to resolve the "ERR_SSL_PROTOCOL_ERROR" error with Vercel. url: /kb/guide/resolve-err-ssl-protocol-error-with-vercel canonical_url: "https://vercel.com/kb/guide/resolve-err-ssl-protocol-error-with-vercel" published: 2025-11-03 last_updated: 2026-08-14 authors: Scott Parker, Anders Morley-Hagström related: - /kb/guide/domain-not-generating-ssl-certificate install_vercel_plugin: npx plugins add vercel/vercel-plugin --- ## Related pages > **For AI agents:** Follow these links to understand how this page connects to the rest of the Vercel ecosystem. For the full cross-link map (inbound, outbound, prerequisites, and semantic neighbors), see the .graph.md link below. - [Working with SSL](https://vercel.com/docs/domains/working-with-ssl?from=related) — Learn how Vercel uses SSL certification to keep your site secure. - [Troubleshooting Domains](https://vercel.com/docs/domains/troubleshooting?from=related) — Learn about common reasons for domain misconfigurations and how to troubleshoot your domain on Vercel. - [Encryption & TLS](https://vercel.com/docs/cdn-security/encryption?from=related) — Learn how Vercel encrypts data in transit and at rest. - [How to resolve IP blocking issues ](https://vercel.com/kb/guide/how-to-resolve-ip-blocking-issues?from=related) — Learn to troubleshoot IP blocking issues for both shared and personal networks. - [Troubleshooting connectivity issues to Vercel Deployments](https://vercel.com/kb/guide/troubleshooting-connectivity-issues?from=related) — Learn how to troubleshoot network connectivity issues to your Vercel deployment. - [Troubleshooting Cross-Origin Errors \\(net::ERR_BLOCKED_BY_ORB\\) with Deployment Protection](https://vercel.com/kb/guide/troubleshooting-cross-origin-errors-neterr-blocked-by-orb-with-deployment-protection?from=related) — Learn to resolve \\`net::ERR_BLOCKED_BY_ORB\\` errors on protected Vercel deployments. This guide explains how cross-origi - [How do I resolve "err_too_many_redirects" when using a Cloudflare proxy with Vercel?](https://vercel.com/kb/guide/resolve-err-too-many-redirects-when-using-cloudflare-proxy-with-vercel?from=related) — Information about how to resolve the "err_too_many_redirects" error when using a Cloudflare proxy with Vercel. - [Why is my Vercel domain not verified?](https://vercel.com/kb/guide/why-is-my-vercel-domain-unverified?from=related) — Information on why a Vercel domain may not be verified and how to verify it. Full cross-link map for this page: [/kb/guide/resolve-err-ssl-protocol-error-with-vercel.graph.md](/kb/guide/resolve-err-ssl-protocol-error-with-vercel.graph.md) Visitors to your site may see `ERR_SSL_PROTOCOL_ERROR`, `ERR_CONNECTION_RESET`, or a page that never finishes loading. These errors share the same underlying causes. This guide shows you how to find the cause with checks you can run in your browser and the Vercel dashboard. ## Check whether the problem is with your site or the network Two checks tell you where the problem lives. 1. Open your deployment's `.vercel.app` URL in the same browser. Every deployment has one, with its own certificate. If it loads while your custom domain shows the error, your application is healthy. The problem is the custom domain's certificate or the network between the visitor and Vercel. 2. Then try your custom domain from a different network or device. Open it on a phone with Wi-Fi turned off so it uses cellular data. If the site loads there but fails on another network, that network is interfering with the connection, and your site is fine. If a visitor sees the error rather than you, ask them to run the same test. ## Check your domain's certificate in the dashboard Vercel automatically issues a TLS certificate for every domain you add. A custom domain without a valid certificate shows these errors to every visitor on every network, while the `.vercel.app` URL keeps working. Open your project's **Settings**, then **Domains**, and check your custom domain's status. A correctly configured domain shows as valid. If it shows as pending or reports an error generating a certificate, follow [Why is my domain not automatically generating an SSL/TLS certificate?](https://vercel.com/kb/guide/domain-not-generating-ssl-certificate) to resolve it, then reload your site. ## Understand why some networks break the connection If the certificate is valid and the error still appears only on some networks, something on those networks is interfering with the secure connection between the visitor's browser and Vercel. Corporate networks, schools, and some internet providers route traffic through security equipment that inspects secure connections before letting them through. That equipment can block a site outright based on the domain's reputation, which it calculates from a range of data sources. It can also break connections by accident. Modern browsers use newer connection security than older equipment expects, and equipment that has not been updated drops the connection instead of completing it. Both failures look identical in the browser, which is why your site can work on a phone over cellular data and fail on an office network minutes later. ## Fix the error on the affected network If the error occurs on a corporate or school network, the fix is the responsibility to whoever runs it. The quickest solution is usually to reach out to the IT team and ask them to investigate. On home or cellular networks, the visitor should raise the issue with their internet provider and mention that the site works on other networks.