The ERR_SPDY_PROTOCOL_ERROR in Google Chrome is a frustrating issue that can prevent users from accessing websites — often Google services like Gmail, YouTube, or others. Although SPDY was a now-deprecated protocol once used to speed up web traffic, some servers and configurations can still trigger this error.

In this guide, you’ll learn what causes this error and how to fix it using practical, easy-to-follow solutions.

What Causes ERR_SPDY_PROTOCOL_ERROR?

This error usually happens due to:

  • Outdated Chrome browser

  • Conflicts with browser cache or cookies

  • VPN/Proxy or antivirus interference

  • Network issues

  • Rare server-side issues

Solution 1: Restart Chrome and Clear DNS Cache

Start with a simple internal Chrome flush.

🔧 Steps:

  1. Open Chrome

  2. In the address bar, go to:

chrome://net-internals/#dns

  1. Click the “Clear host cache” button

  2. Restart Chrome and revisit the site.

📌 Example: This often fixes the issue if you’re trying to access YouTube or Gmail and have had browser tabs open for too long.

Solution 2: Update Chrome to the Latest Version

An outdated Chrome version may still reference the obsolete SPDY protocol.

Some useful steps:

  1. Open Chrome

  2. Click the three dots in the top-right → Help → About Google Chrome

  3. Chrome will automatically check and install the latest update

  4. Restart your browser

📌 Example: If you’re getting this error on multiple sites and haven’t updated in a while, this is your first go-to fix.

Solution 3: Clear Browser Cache and Cookies

Corrupted cookies or cache can conflict with secure protocols.

🔧 Steps:

  1. Press Ctrl + Shift + Delete(Windows) or Cmd + Shift + Delete (Mac)

  2. Choose “All time” as the time range

  3. Check Cookies and other site data and Cached images and files

  4. Click Clear data

📌 Example: If only a specific site like Reddit.com throws the error, clearing cache can fix local conflicts.

Solution 4: Flush Your System DNS Cache

Sometimes the error stems from your operating system’s DNS cache.

🔧 Windows:

  1. Open Command Prompt as Administrator

  2. Run:

ipconfig /flushdns

  1. Restart Chrome

🔧 macOS:

  1. Open Terminal

  2. Run:

sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder

📌 Example: This is helpful if you recently changed networks or DNS settings.

Solution 5: Disable Antivirus or Firewall (Temporarily)

Some antivirus or internet security tools block SPDY-based connections or behave aggressively toward HTTPS traffic.

🔧 Steps:

  1. Disable your antivirus/firewall temporarily

  2. Retry accessing the website

  3. If it works — whitelist the site or switch to a different security suite

📌 Example: Avast and AVG have previously been known to cause conflicts with Google services.

Solution 6: Try Incognito Mode or Another Browser Profile

Browser extensions or profile-specific settings can cause SPDY errors.

🔧 Steps:

  1. PressCtrl + Shift + Nto open Incognito mode

  2. Try accessing the same website

If it works:

  • Disable all extensions and enable them one by one via chrome://extensions/

  • Or, create a new Chrome profile via Settings → You and Google → Add new user

📌 Example: Ad blockers or VPN extensions like Hola or ZenMate can interfere with protocol handling.

What if Nothing Works?

If none of the above methods resolve the issue, consider:

  • Trying another browser (Edge, Firefox) to rule out Chrome-specific issues

  • Contacting the website’s support if only one domain shows the error

  • Checking for system malware or using Chrome Cleanup Tool (on Windows)