Opening a website only to see a 401 error message? This is one of the most common access issues on the web. Good news — most cases can be fixed yourself in just a few minutes.
Error 401 means the server denies access to the requested page due to authentication problems. In simpler terms, the server cannot verify that you have permission to view this content.
Unlike many server errors (500, 502, 503), the 401 problem usually originates on the client side — meaning in your browser or device. This makes diagnosis and troubleshooting much easier.
What Does Error 401 Look Like
Web servers and browsers display error 401 differently. Here are typical message variations:
Standard Variations:
- 401 Unauthorized
- 401 Authorization Required
- HTTP 401
- HTTP Error 401 – Unauthorized
- Access Denied
In Browsers:
- Chrome: "401. That's an error. The page you requested requires authentication."
- Firefox: "Authorization Required. This server could not verify that you are authorized to access the document requested."
- Safari: "Authentication Required"
On Servers:
- Apache: "401 - Unauthorized: Access is denied due to invalid credentials."
- Nginx: "401 Authorization Required"
- IIS: "HTTP Error 401.0 - Unauthorized. You do not have permission to view this directory or page."
Despite different wording, all these messages point to one status code — 401. The code, not the message text, helps accurately identify the problem.
Main Causes of 401 Error
Let's examine the most common reasons this error appears. Understanding the source is the first step to solving it.
1. Incorrect Credentials
The most obvious cause — entering wrong username or password. Even experienced users sometimes make mistakes when typing, especially with complex passwords.
The problem worsens when:
- Autofill is enabled and browser inserts old password
- You recently changed password but browser remembers previous one
- Caps Lock is on or wrong keyboard layout active
- Password contains special characters typed differently on various keyboards
2. Expired Cookies and Browser Cache
Modern browsers store session information in cookies. These small files contain authentication tokens that confirm your identity on repeat visits.
When cookies expire or become corrupted, server cannot recognize your session. Browser cache works similarly — temporary storage for site files. If cache contains outdated authentication data, conflict occurs between old and current information.
Typical situations:
- Haven't visited site for long time and session expired
- Crash occurred during page refresh
- Site administrator reset all active sessions
- Browser incorrectly saved authentication data
3. Incorrect or Outdated URL
Typo in address bar easily leads to 401 error. Protected site sections requiring authorization are especially tricky.
Imagine: administrator renamed page from /admin to /dashboard, but you continue using old bookmark. Server sees attempt to access nonexistent address through outdated authorization path and returns 401.
Problem also arises when:
- Page moved to different section
- URL structure changed after site update
- Copying link from old email or document
- Using shortened links leading to deleted pages
4. Security Plugin Conflicts
Site protection plugins sometimes work too zealously. This especially concerns WordPress, where popular plugins like Wordfence, iThemes Security, All In One WP Security can block legitimate login attempts.
Blocking reasons:
- Exceeded allowed number of failed login attempts
- Your IP address blacklisted by plugin
- Geo-blocking — plugin blocks connections from certain countries
- Too strict traffic filtering rules
- Conflict between multiple security plugins
Particularly tricky situation when you just installed new security plugin. It may immediately block access even to administrator until you configure exceptions.
5. DNS Cache Issues
Domain Name System (DNS) translates readable addresses like example.com into numeric IP addresses. Your computer saves these matches in local cache to speed up work.
But if site moved to new server with different IP address, your outdated DNS cache continues sending requests to old server. New server doesn't know about your authorization on old one — hence error 401.
DNS problem especially relevant after:
- Site migration to new hosting
- DNS server changes
- Enabling CDN or proxy service like Cloudflare
- Technical maintenance on hosting provider side
6. Server-Level Password Protection
Many administrators configure additional password protection through web server configuration. This is basic HTTP authentication requesting login and password before site itself loads.
On Apache such protection configured through .htaccess and .htpasswd files. On Nginx — through auth_basic directive in configuration. If you don't know these credentials or they changed, you get error 401.
Typical situations:
- Developer password-protected test version of site
- Admin panel closed with additional authentication layer
- Access restrictions set for certain folders
- Server requires authorization for statistics or logs
7. Expired API Tokens
If you're developing application or configuring integration with external services, cause of 401 may be API token problems.
Modern APIs use access tokens with limited validity period. When token expires, service no longer accepts your requests. OAuth 2.0, JWT (JSON Web Tokens) and other authorization mechanisms require regular token updates.
Common problems:
- Access token expired and requires refresh
- Error in request header — token transmitted incorrectly
- API key deleted in service control panel
- Token access rights changed
- Application uses hardcoded token instead of dynamic update
8. Multi-User Platform Conflicts
On sites with role and permission systems, error 401 occurs when attempting to get content above your access level.
For example:
- User tries opening admin panel
- Guest enters section only for registered users
- Author tries editing someone else's article
- Premium subscription expired
WordPress, Joomla, Drupal and other CMS may show 401 instead of more logical error 403 (Forbidden) with incorrect permission check configuration.
Step-by-Step Solutions for 401 Error
Now let's move to practical solutions. Follow instructions sequentially — from simple methods to more complex.
Method 1: Verify URL Correctness
Start with most obvious. Carefully examine address in browser bar:
- Ensure no typos in domain name
- Check path correctness after domain
- Pay attention to character case — some servers distinguish
/Adminfrom/admin - Check for extra spaces at beginning or end of address
- Ensure using
https://nothttp://if site works only via secure protocol
If address copied from old email or document, try going to site homepage and navigating to needed section through menu.
Method 2: Check Credentials
Even if confident in username and password correctness, double-check:
Simple verification:
- Disable autofill in browser
- Enter username and password manually
- Ensure Caps Lock is off
- Check keyboard layout
- Watch for spaces at beginning and end
If didn't help:
- Use "Show password" function when entering
- Copy password from reliable password manager
- Try logging in from different device
- Use password recovery function
Often problem solved by simple reset and creating new password.
Method 3: Clear Cookies and Browser Cache
Outdated authentication data in browser — frequent cause of error 401. Clearing will fix problem:
Google Chrome:
- Press
Ctrl+Shift+Delete(Windows/Linux) orCmd+Shift+Delete(Mac) - Select time range "All time"
- Check "Cookies and other site data" and "Cached images and files"
- Click "Clear data"
Mozilla Firefox:
- Press
Ctrl+Shift+Delete - Select range "Everything"
- Check "Cookies" and "Cache"
- Click "Clear Now"
Safari:
- Open Safari → Preferences → Privacy
- Click "Manage Website Data"
- Select needed site or "Remove All"
- Confirm deletion
After clearing, close and reopen browser. On next login you'll get fresh cookies.
Method 4: Try Incognito Mode
Private browsing mode allows testing site without influence of saved dаta:
- Chrome:
Ctrl+Shift+N(Windows/Linux) orCmd+Shift+N(Mac) - Firefox:
Ctrl+Shift+P - Safari:
Cmd+Shift+N
Open problematic site in incognito mode. If error disappeared — problem definitely in cookies or cache of main profile. If error remained — cause goes deeper.
Method 5: Flush DNS Cache
Outdated DNS records direct your requests to wrong server. Cache flushing forces system to request current addresses.
Windows:
- Open command prompt as administrator
- Execute command:
ipconfig /flushdns - See message: "Successfully flushed the DNS Resolver Cache"
- Restart browser
macOS:
- Open Terminal
- Execute command:
sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder - Enter administrator password
- Restart browser
Linux:
- Open terminal
- Execute:
sudo systemd-resolve --flush-caches - Or:
sudo /etc/init.d/nscd restart(for systems with nscd)
After DNS flush, wait 1-2 minutes before retry accessing site.
Method 6: Disable Plugins and Browser Extensions
Some extensions block cookies, modify request headers or interfere with authorization process.
Suspicious extension types:
- Ad blockers (AdBlock, uBlock Origin)
- VPN and proxy services
- Privacy managers
- Antivirus extensions
- HTTP header modifiers
How to check:
- Disable all browser extensions
- Try accessing problematic site
- If worked — enable extensions one by one
- Identify conflicting extension
- Update or remove problematic extension
Method 7: Deactivate WordPress Security Plugins
If you have access to WordPress admin panel through different device or after cache clearing:
Through admin panel:
- Go to "Plugins" → "Installed"
- Deactivate security plugins: Wordfence, iThemes Security, All In One WP Security
- Try logging in again
- If helped — check plugin settings
- Add your IP to whitelist
Through FTP/file manager: If admin access completely blocked:
- Connect to site via FTP
- Navigate to
/wp-content/plugins/ - Rename problematic plugin folder (e.g.,
wordfencetowordfence-disabled) - WordPress automatically deactivates plugin
- Log into admin and fix settings
- Restore original folder name
Method 8: Check .htaccess File
On Apache servers .htaccess file controls many parameters including directory access.
Temporary .htaccess disable:
- Connect via FTP or through hosting file manager
- Find
.htaccessfile in site root folder - Rename it to
.htaccess-old - Try accessing site
- If worked — problem in
.htaccessconfiguration
Typical problematic lines:
# Password protection
AuthType Basic
AuthName "Restricted Area"
AuthUserFile /path/to/.htpasswd
Require valid-user
# IP blocking
Order Deny,Allow
Deny from all
Allow from 192.168.1.1If unsure about edits, create new .htaccess with basic WordPress settings:
# BEGIN WordPress
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
# END WordPressMethod 9: Remove Directory Password Protection
If folder protected with basic HTTP authentication:
- Find
.htpasswdfile in protected directory - Create backup copy
- Delete
.htpasswdfile - Delete or comment out
AuthType,AuthName,AuthUserFile,Requirelines in.htaccess - Check access
Alternative — password update:
- Use online htpasswd generator
- Create new username:password pair
- Replace
.htpasswdcontents with new data - Use new credentials for login
Method 10: Check WWW-Authenticate Header
For advanced users — server response analysis shows exact authentication method:
Chrome DevTools:
- Open problematic page
- Press
F12to open developer tools - Go to "Network" tab
- Refresh page (
F5) - Find request with 401 code
- Click on it
- Go to "Headers" tab
- Find "Response Headers" section
- Study
WWW-Authenticateline
Example values:
WWW-Authenticate: Basic realm="Restricted Area"
WWW-Authenticate: Bearer realm="example"
WWW-Authenticate: Digest realm="testrealm@host.com", qop="auth"
This tells which exact authentication method server uses and where to look for problem.
Method 11: Update API Tokens
For developers working with APIs:
Basic diagnostics:
- Check token expiration
- Ensure token passed in correct header (
Authorization: Bearer YOUR_TOKEN) - Check token scope
- Ensure token not revoked
Token update:
- Use refresh token to get new access token
- Ensure refresh token also not expired
- If both tokens expired — authorize again
- Save tokens in secure storage
- Implement automatic token update before expiration
Method 12: Contact Technical Support
If no method helped:
Preparation for contact:
- Gather problem information: when started, what preceded, tried solutions above
- Take error screenshot
- Check site operation through online services like isitdownrightnow.com
- Try accessing from different device/network
Where to contact:
- Hosting provider — if problem on entire site
- Site developer — if problem in specific functionality
- CMS support forum — if problem in WordPress, Joomla etc.
- Plugin creator — if problem appeared after plugin update
THE.Hosting provides 24/7 technical support. Specialists will help diagnose server causes of error 401 and restore access to your site.
Difference Between 401 and 403 Errors
Both errors related to access, but have different meaning:
401 Unauthorized:
- Server doesn't know who you are
- You didn't provide credentials or they're incorrect
- Problem solved with proper authorization
- This is "temporary" problem — enter correct data and get access
403 Forbidden:
- Server knows who you are but denies access
- Your credentials correct but permissions insufficient
- Administrator explicitly blocked resource access
- This is "permanent" problem — even with correct data access closed
Example of difference:
Imagine private club:
- 401 — guard doesn't let you in because you didn't show membership card (not authorized)
- 403 — guard checked your card but you don't have VIP zone access (insufficient permissions)
When to show what:
- Wrong username/password → 401
- Login attempt without authorization → 401
- Expired session → 401
- Insufficient user permissions → 403
- Access blocked by administrator → 403
- IP on blacklist → 403
Proper configuration of these error codes important not only for users but also for site security.
How to Prevent 401 Error
Prevention always better than cure. Following measures will reduce risk of access problems.
For Site Owners
1. Proper Authorization Setup
Ensure authorization system configured correctly:
- Adequate session duration (not too short)
- Proper token expiration handling
- Correct "Remember me" function operation
- Clear error messages (not just 401, but reason explanation)
2. Security Plugin Monitoring
Regularly check:
- Blocked IP address list
- Failed login attempt logs
- Traffic filtering rules
- Geo-blocking settings
Add your work IPs to whitelist to avoid accidental blocking.
3. Configuration Backup
Keep backups of critical files:
.htaccess.htpasswd- CMS configuration files
- Security plugin settings
Quickly restore working configuration when problems arise.
4. Settings Documentation
Maintain documentation:
- Which folders password-protected and why
- Credentials for service section access
- Security setting change history
- Developer and support service contacts
5. Testing After Updates
After each update check:
- Authorization operation on all pages
- Protected section accessibility
- API integration correctness
- Server logs for 401 errors
For Users
1. Password Management
Use password manager:
- Stores complex unique passwords
- Automatically fills login forms
- Synchronizes between devices
- Warns about password leaks
Recommended managers: 1Password, Bitwarden, KeePass.
2. Regular Browser Cleaning
Periodically clear:
- Cookies older than 3 months
- Cache when sites behave strangely
- Download and search history
Configure automatic cleaning on browser close for maximum privacy.
3. Software Updates
Keep up to date:
- Operating system
- Browser
- Antivirus
- Browser extensions
Old versions may contain bugs in authorization handling.
4. Extension Checking
Be careful with extensions:
- Install only from official stores
- Check rating and reviews
- Monitor requested permissions
- Remove unused extensions
5. Network Security
When working with sensitive dаta:
- Avoid public Wi-Fi networks
- Use VPN on unreliable connections
- Don't save passwords on publicly accessible computers
- Always log out of accounts after work
Frequently Asked Questions
What does error 401 Unauthorized mean?
This is HTTP status code indicating server request cannot be completed due to missing or incorrect authorization data. Server requires identity confirmation but didn't receive it or received incorrect one.
What's difference between 401 and 403 errors?
401 means you need to authorize — you didn't provide credentials or they're wrong. 403 means you're authorized but lack access permissions to requested resource. Simply put: 401 — "I don't know who you are", 403 — "I know who you are, but you can't access this".
Why does error 401 appear only in one browser?
Each browser stores cookies and cache independently. If one browser has outdated or corrupted authorization data, it will get error 401 while other browsers work normally. Clearing cookies and cache of problematic browser will solve problem.
Can error 401 be caused by antivirus?
Yes, antivirus programs sometimes block or modify cookies, intercept SSL connections or block certain web traffic types. Try temporarily disabling antivirus and checking site access. If helped — add site to antivirus exceptions.
What to do if error 401 appears on site that worked before?
First clear cookies and browser cache — this solves most cases. If didn't help: check if password changed, try different browser or device, flush DNS cache. If problem widespread — likely technical maintenance on server, wait 1-2 hours.
How to fix error 401 in WordPress?
Most common causes in WordPress: security plugin conflict, .htaccess file problems, incorrect file permissions. Deactivate security plugins, rename .htaccess, check file permissions via FTP. If doesn't help — restore site from backup.
Why does error 401 appear after site update?
Updates can change security settings, database structure or server configuration. After updating WordPress, plugins or theme check: plugins not conflicting, permalink settings not changed, .htaccess file not corrupted. Often helps re-saving permalink settings.
How to protect admin panel from 401 errors?
Use reliable security plugin with correct settings, add your IP to whitelist, configure two-factor authentication, limit login attempts, change standard login address from /wp-admin to something unique. Keep backup FTP access in case of blocking.
Conclusion
Error 401 Unauthorized though seems scary, in most cases easily eliminated. Main thing — systematically check possible causes: from simple password typo to complex security plugin conflicts.
Start diagnosis with basic solutions: check URL, clear cookies and cache, try different browser. If simple methods didn't help — move to more specific: plugin deactivation, .htaccess check, server header analysis.
Remember prevention: regularly update software, use password manager, make configuration backups. This saves time and nerves when problems arise.
THE.Hosting VPS ensures stable web application operation with advanced security settings. Our technical support works 24/7 and helps diagnose cause of error 401 at any level — from client to server.