How to Fix ADP Error Code 100 (June 2026) – 10 Working Solutions

ADP Error Code 100 typically means your ADP account is locked, your login credentials are incorrect, or your company’s Single Sign-On (SSO) configuration (Okta, SAML, Active Directory) has an employee-number mismatch. The fastest fix for most users is to contact their company’s HR or payroll administrator and ask them to unlock the account or verify the employee ID was added to your Active Directory profile.

If you are seeing the “Error 100 please see administrator” message while trying to access ADP Workforce Now, ADP Run, my.adp.com, or the ADP mobile app in 2026, this guide walks through every working solution. We cover the standard browser and credential fixes plus the enterprise root causes that Reddit IT admins, AutoZone employees, Amazon new hires, and ADP practitioners report most often.

This page is fully updated for 2026, so you will not find stale references to Internet Explorer, Windows 8.1, or 2018-era browser versions. Every system requirement, support path, and troubleshooting step reflects the current ADP platform.

What Does ADP Error Code 100 Mean?

ADP Error Code 100 is a generic access-denied message returned by the ADP login gateway. It is ADP’s way of saying that the platform cannot verify your identity or your employer’s configuration, so it blocks entry to payroll, pay statements, W-2 forms, direct deposit settings, and benefits screens until the underlying problem is corrected.

What makes this error confusing is that the on-screen text rarely explains the actual cause. The message usually reads “Error 100 please see administrator,” which gives no hint about whether the problem is a typo, a locked account, an Okta SAML misconfiguration, or a missing employee number in Active Directory. That is why so many users end up searching Reddit and ADP support threads for the real fix.

Based on reports from r/ADP, r/AmazonFC, and r/AutoZone, along with enterprise IT administrator feedback, the most common root causes break down into four categories. Credential problems (wrong username, forgotten password, case-sensitivity mistakes) account for a large share of cases. Account lockouts, triggered by repeated failed sign-in attempts, are another leading cause. Browser or device issues, including corrupted cache, outdated browsers, and conflicting extensions, account for a third group. Finally, enterprise configuration problems, such as an Okta SSO integration missing the correct SAML metadata or an employee number not being added to the Active Directory profile, are the dominant cause for new hires and SSO users.

Understanding which category your situation falls into is the key to resolving the error quickly. If you are a brand-new employee who has never logged in before, the cause is almost always an account setup or SSO configuration issue rather than a browser problem. If you have been logging in fine for months and suddenly hit Error 100, a locked account or expired password is far more likely.

Quick Summary of Solutions

Before diving into the detailed steps, here is a fast overview of all 10 solutions covered in this guide. Try them in order, because the first few address the most common causes.

1. Contact your HR or payroll administrator to check whether your account is locked or your employee number is missing from Active Directory. This is the single most effective fix for Error 100.
2. Reset your password through the ADP login page at my.adp.com if you suspect a forgotten or mistyped password.
3. Verify your login credentials and watch for case-sensitivity and autocorrect errors.
4. Clear browser cache and cookies to remove corrupted stored data that can interfere with the ADP session.
5. Update your browser to the latest stable release of Chrome, Firefox, Edge, or Safari.
6. Disable browser extensions and add-ons that may conflict with ADP’s login scripts.
7. Enable JavaScript and cookies in your browser privacy settings.
8. Switch to a different browser to rule out browser-specific compatibility glitches.
9. Check your network connection and ADP service status to rule out outages.
10. Verify current system compatibility requirements and contact ADP Customer Support if nothing else works.

How To Fix ADP Error Code 100 in 2026?

1. Contact Your HR or Payroll Administrator First

This solution is listed first for a reason. Forum reports from IT administrators, Amazon new hires, and AutoZone employees consistently show that the most common real-world cause of ADP Error Code 100 is a locked account or a missing employee number in Active Directory. No amount of cache clearing or password resetting will fix an account that has not been properly provisioned.

When you see the “please see administrator” wording, ADP is often being literal. Your company’s payroll administrator, HR contact, or IT help desk has tools to check whether your account exists, whether it is locked, and whether your employee ID has been correctly linked to your ADP profile. Reach out to them with the following details ready.

• Your full legal name exactly as it appears on your pay stub or onboarding paperwork.
• Your employee ID or associate number, if you have been given one.
• The exact text of the error message, including the words “Error 100 please see administrator.”
• The ADP product you are trying to reach, such as Workforce Now, ADP Run, or the ADP mobile app.
• Whether you access ADP through Okta, Microsoft Entra ID (formerly Azure AD), or another SSO provider.

Ask the administrator specifically to confirm that your employee number has been added to your Active Directory profile. Reddit IT admins report that this is the single most common root cause, especially for new hires, because the ADP number is sometimes never populated in AD during onboarding. Once the admin adds or corrects the employee number and re-syncs the directory, Error 100 typically clears within minutes.

If your administrator confirms the account is locked from too many failed login attempts, they can unlock it on their side. After unlocking, wait 10 to 15 minutes before trying to sign in again, because the lockout state can take time to propagate through ADP’s servers.

2. Reset Your Password

If your administrator confirms the account is not locked and your employee ID is correct, the next most likely cause is a forgotten or mistyped password. ADP passwords are case-sensitive, and the platform enforces periodic password resets, so an old password stored in your browser or password manager may simply be expired.

Step 1: Open the ADP login page

Go to the official ADP sign-in page at my.adp.com. Do not use bookmarked links from older emails, because ADP occasionally updates its login URLs and old bookmarks can redirect to stale pages that produce errors.

Step 2: Click “Forgot Your Password?”

Below the password entry field, click the “Forgot Your Password?” link. This opens the ADP self-service password reset flow, which works for both Workforce Now and ADP Run users.

Step 3: Enter your user ID or registered email

Provide the user ID or email address associated with your ADP account. If you are a new hire and have not yet received a user ID, you will need a registration code from your employer instead of using the password reset flow.

Step 4: Verify your identity

ADP will send a verification code to your registered email or phone number. Enter the code when prompted. If you no longer have access to the phone number on file, you will need to contact your HR administrator to update your contact details before you can reset the password.

Step 5: Create a new password

Choose a new password that combines uppercase and lowercase letters, numbers, and special characters. Avoid reusing a previous ADP password, because ADP remembers recent passwords and will reject them.

Step 6: Sign in with the new credentials

Return to my.adp.com and log in with your new password. If the error persists after a successful password reset, the problem is almost certainly an account configuration issue on the administrator side rather than a credential problem.

3. Double-Check Your Login Credentials

Before escalating further, take one careful pass through your credential entry. ADP usernames are often tied to your company email address or an employee ID assigned during onboarding. A single mistyped character will produce Error 100 because the system cannot match your input to a valid profile.

• Type your password manually rather than relying on autofill, which can silently insert an outdated password.
• Check the Caps Lock and Num Lock keys, because ADP passwords are case-sensitive.
• Confirm the username format your company uses. Some employers use firstname.lastname, others use a numeric employee ID, and others use the full company email address.
• Disable autocorrect and autocorrect extensions, which can change capitalization or insert spaces inside usernames.

If you have multiple ADP accounts (for example, from a previous employer), make sure you are signing in with the credentials tied to your current employer’s ADP instance. Mixing accounts from different companies is a common source of Error 100.

4. Clear Browser Cache and Cookies

Browsers store cached versions of pages, session tokens, and cookies to speed up loading. When ADP updates its login flow, these stored files can become stale or corrupted, causing the sign-in page to behave unexpectedly and return Error 100. Clearing cache and cookies forces the browser to fetch fresh data from ADP’s servers.

Google Chrome

1. Click the three-dot menu in the top-right corner and choose Settings.
2. Go to Privacy and security, then click Clear browsing data.
3. Select All time as the time range.
4. Check Cookies and other site data and Cached images and files.
5. Click Clear data and restart Chrome.

Mozilla Firefox

1. Click the hamburger menu in the top-right corner and select Settings.
2. Go to Privacy and Security and scroll to Cookies and Site Data.
3. Click Clear Data and check both Cookies and Site Data and Cached Web Content.
4. Click Clear, then restart Firefox.

Microsoft Edge

1. Click the three-dot menu and choose Settings.
2. Go to Privacy, search, and services, then under Clear browsing data click Choose what to clear.
3. Select All time, then check Cookies and other site data and Cached images and files.
4. Click Clear now and restart Edge.

Safari (macOS)

1. From the Safari menu bar, choose Settings (Preferences on older macOS versions).
2. Go to the Privacy tab and click Manage Website Data.
3. Click Remove All, then confirm.
4. From the Safari menu, choose Clear History, select All history, and click Clear History.

After clearing cache and cookies, navigate back to my.adp.com and attempt to sign in. If Error 100 disappears, the cause was stale stored data.

5. Update Your Browser

ADP Workforce Now and ADP Run rely on modern web standards that older browsers do not fully support. Running an outdated browser can cause login scripts to fail silently, returning Error 100 even with correct credentials.

All major browsers now auto-update by default, but auto-update can be paused by IT policy or fail silently on managed devices. Use the steps below to confirm you are on the latest stable release.

Google Chrome

1. Type chrome://settings/help in the address bar and press Enter.
2. Chrome will automatically check for updates and install them.
3. Click Relaunch if prompted to restart the browser.

Mozilla Firefox

1. Type about:preferences in the address bar and press Enter.
2. Scroll to Firefox Updates and click Check for Updates.
3. Restart Firefox if an update is installed.

Microsoft Edge

1. Type edge://settings/help in the address bar and press Enter.
2. Edge will check for and install any available update.
3. Click Restart to finish the update.

Safari

Safari updates are bundled with macOS updates. Open System Settings, go to General, then Software Update, and install any available macOS update. Safari cannot be updated independently.

6. Disable Browser Extensions and Add-Ons

Browser extensions, particularly ad blockers, privacy shields, script blockers, and password managers, can interfere with the JavaScript that powers the ADP login page. When a critical script is blocked, ADP may fail to authenticate the session and return Error 100.

The fastest way to test for an extension conflict is to open a private or incognito window with extensions disabled, then try to log in. If ADP loads successfully in private mode, one or more extensions are the culprit.

Google Chrome

1. Type chrome://extensions in the address bar.
2. Toggle off each extension one by one.
3. Reload my.adp.com after each toggle to identify the conflicting extension.

Mozilla Firefox

1. Type about:addons in the address bar.
2. Click Extensions in the sidebar.
3. Disable each extension and reload ADP to isolate the conflict.

Microsoft Edge

1. Type edge://extensions in the address bar.
2. Toggle off each extension and reload ADP to test.

Once you identify the offending extension, you can leave it disabled for the ADP domain only or replace it with an alternative that does not block ADP’s login scripts.

7. Enable JavaScript and Cookies

ADP’s login gateway requires both JavaScript and cookies to maintain a valid session. If a strict privacy setting or a corporate policy disables either, the login attempt will fail with Error 100.

Google Chrome

1. Go to Settings, then Privacy and security, then Site Settings.
2. Under Content, click JavaScript and set it to Sites can use JavaScript.
3. Return to Site Settings, click Cookies and site data, and set it to Allow all cookies.

Mozilla Firefox

1. Go to Settings, then Privacy and Security.
2. Under Enhanced Tracking Protection, select Standard or Custom and ensure adp.com is not blocked.
3. JavaScript is enabled by default in Firefox and can only be changed in about:config. Leave javascript.enabled set to true.

Microsoft Edge

1. Go to Settings, then Cookies and site permissions.
2. Under All permissions, click JavaScript and ensure it is allowed.
3. Click Manage and delete cookies and site data and ensure cookies are allowed.

Safari (macOS)

1. From the Safari menu, choose Settings.
2. On the Privacy tab, ensure Block all cookies is unchecked.
3. On the Security tab, confirm that JavaScript is enabled.

8. Switch to a Different Browser

If Error 100 persists across all of the fixes above, the issue may be specific to your current browser’s profile, an extension conflict you cannot isolate, or a browser-specific rendering bug. Switching to a different browser is a quick way to confirm whether the problem is environment-related.

Download and install one of the supported browsers listed in the compatibility section below, then navigate to my.adp.com and attempt to sign in. If login succeeds, you can either continue using the new browser for ADP or troubleshoot the original browser’s profile more deeply.

For users on managed corporate devices, switching browsers may not be possible due to IT restrictions. In that case, ask your IT administrator to verify that ADP domains are added to the trusted sites list and that no proxy or firewall policy is stripping session cookies.

9. Check Network Connectivity and ADP Service Status

Network problems can mimic Error 100 by interrupting the authentication handshake between your browser and ADP’s servers. Corporate VPNs, captive Wi-Fi portals, and DNS-level filtering are common culprits.

• Restart your modem and router by unplugging them for 30 seconds.
• If you are on a corporate VPN, disconnect and reconnect, or try signing in without the VPN if your IT policy allows.
• Run a speed test at speedtest.net or fast.com to confirm your connection is stable.
• Try loading a few non-ADP websites to verify general connectivity.
• Check ADP’s official service status page and the @ADP Twitter account for outage notices.

If your employer routes ADP traffic through a corporate proxy, ask IT whether adp.com is being inspected or blocked. Proxy inspection can strip security headers and cause ADP to reject the session with Error 100.

10. Verify Current ADP System Compatibility Requirements

ADP’s web platform is updated regularly, and using an unsupported operating system or browser version can trigger Error 100 because required security protocols and JavaScript features will be missing. The requirements below reflect the current ADP platform in 2026. Older guidance that referenced Windows 8.1, macOS Sierra, Chrome 71, Firefox 64, Safari 12, or Internet Explorer is outdated and should be disregarded.

Supported Operating Systems

• Windows: Windows 10 (with current updates) or Windows 11. Earlier versions such as Windows 8.1 and Windows 7 are no longer supported by Microsoft and may fail to load ADP correctly.
• macOS: macOS 13 Ventura, macOS 14 Sonoma, or macOS 15 Sequoia. Apple provides the latest version of Safari only on currently supported macOS releases.
• Mobile: iOS 16 or later for iPhone and iPad; Android 12 or later for Android phones and tablets.

Supported Browsers

• Google Chrome: Latest stable version (Chrome auto-updates, so the most recent release is what ADP tests against).
• Mozilla Firefox: Latest stable version.
• Microsoft Edge: Latest stable version based on Chromium.
• Apple Safari: Latest stable version on macOS only.

Internet Explorer is no longer supported by Microsoft or by ADP. If you are still using Internet Explorer, switch to Microsoft Edge or another supported browser before attempting to log in. Microsoft Edge has a built-in Internet Explorer mode for legacy enterprise apps, but ADP’s login gateway is not one of them and will return errors.

Additional Requirements

• JavaScript must be enabled.
• Cookies must be allowed, including third-party cookies for adp.com if your browser blocks them by default.
• A stable broadband connection with low latency is recommended for the ADP Workforce Now admin console.
• Screen resolution of at least 1280 by 720 for the full admin experience.

To confirm your setup, check your OS version in Windows under Settings, System, About, or on macOS under the Apple menu, About This Mac. To check your browser version, open chrome://settings/help, edge://settings/help, about:preferences in Firefox, or About Safari in the Safari menu. Apply any available updates before trying ADP again.

Account Lockout: A Common Hidden Cause

ADP automatically locks accounts after a certain number of failed login attempts to protect against brute-force attacks. Once locked, every subsequent sign-in attempt, even with the correct password, will return Error 100 until the lock is cleared by an administrator or until the lockout timer expires.

This is why so many users report that Error 100 “appears out of nowhere” after they finally remembered the right password. By the time they enter the correct credentials, the account is already locked from the earlier failed attempts, and no amount of correct typing will get them in.

How to Tell If Your Account Is Locked

ADP does not always display a clear “account locked” message. Instead, you may see the same “Error 100 please see administrator” prompt that appears for other causes. The clearest way to confirm a lockout is to ask your HR or payroll administrator to check your account status in the ADP admin console.

How to Unlock an ADP Account

• Ask your company HR, payroll, or IT administrator to unlock the account from the ADP admin console.
• If your company uses Okta or another SSO provider, ask the IT team to reset your SSO session.
• Wait for the automatic lockout timer to expire, which can range from 15 minutes to several hours depending on company policy.
• After unlocking, perform a single password reset through my.adp.com to start with a known good credential.

Avoid repeated guessing while the account is locked, because each attempt can extend the lockout period and in some cases trigger a longer security hold.

SSO, Okta, SAML, and Active Directory Troubleshooting

If your company logs into ADP through Okta, Microsoft Entra ID (formerly Azure AD), or another federated single sign-on provider, Error 100 is very often a configuration problem rather than a user error. Reddit’s r/ADP community is full of IT administrators who report that new hires hit Error 100 specifically because their employee number was never added to their Active Directory profile.

Common SSO Causes of Error 100

• Missing employee number in Active Directory. ADP matches the SSO claim to an employee record. If the employee number is blank or wrong in AD, the match fails and Error 100 is returned.
• Stale SAML metadata. If the SAML metadata XML file uploaded to ADP is out of date, the certificate trust chain breaks and authentication fails.
• Incorrect claim mapping. The SSO provider must send the correct claim (typically the employee number or a configured ADP attribute). A misconfigured claim name will cause ADP to reject the login.
• New hire provisioning delay. Even after HR creates the employee record, it can take hours or overnight for the SSO identity to propagate to ADP.
• Multiple employee records. A duplicate record in ADP can confuse the SSO match logic and produce Error 100.

Steps for IT Administrators

1. Open Active Directory and verify the affected user’s profile contains the correct ADP employee number in the appropriate attribute field.
2. Confirm the employee number in AD exactly matches the employee ID listed in the ADP admin console.
3. Check the SSO provider (Okta, Entra ID, etc.) and confirm the ADP application is configured to send the employee number as the matching claim.
4. Verify the SAML metadata XML file uploaded to ADP matches the current certificate from your SSO provider. Re-upload the metadata if the certificate was renewed.
5. Force a directory sync between your identity provider and ADP, then ask the user to attempt login again.
6. Open a ticket with ADP support and request escalation if the issue persists across multiple users, because SAML configuration changes sometimes require an ADP representative to apply them on the back end.

Reddit administrators report that escalating repeatedly is sometimes necessary. One IT admin shared that they “created 4 and escalated every single ticket with ADP” before a SAML metadata configuration issue was resolved, so persistence is part of the process for enterprise SSO cases.

Steps for End Users on SSO

If you are not an administrator, your options are more limited, but you can still take productive steps. Tell your IT help desk specifically that you suspect an SSO configuration issue and mention the employee number in Active Directory. This gives the help desk a concrete starting point rather than a generic “I cannot log in” ticket.

If your company uses the ADP Bridge feature and you see Error 100 only when accessing the Bridge, open a trouble ticket with ADP directly. Practitioners on Reddit note that ADP’s response time on Bridge-related tickets can be slow, so escalating through your ADP account representative is often faster than waiting on the standard support queue.

ADP Mobile App Error 100 Troubleshooting

The ADP mobile app, used by many employees to check pay stubs and direct deposit details, can also display Error 100. Amazon new hires using the A-to-Z app to access ADP have reported Error 100 specifically when verifying direct deposit information during onboarding.

Update the ADP Mobile App

Outdated app versions are a frequent cause of mobile Error 100. Open the App Store on iOS or Google Play on Android, search for ADP Mobile Solutions, and install any available update. If the update does not appear, uninstall and reinstall the app to ensure you have the current version.

Clear the ADP App Cache (Android)

1. Open Settings on your Android device.
2. Go to Apps, then find and tap ADP Mobile Solutions.
3. Tap Storage, then tap Clear Cache and Clear Data.
4. Reopen the app and sign in.

Offload and Reinstall the App (iOS)

1. Open Settings, then General, then iPhone Storage.
2. Find ADP Mobile Solutions and tap Offload App.
3. Tap Reinstall App to restore a fresh copy without losing your data.
4. Open the app and attempt to sign in.

Check App-Specific Account Setup

If you are a new hire accessing ADP through Amazon A-to-Z, AutoZone’s employee portal, or another third-party app, the integration itself can be the source of Error 100. Confirm with your employer that your employee record has been fully activated in ADP before trying to link the third-party app. Many onboarding flows require a one-time setup step inside my.adp.com directly before the mobile app will work.

Switching between Wi-Fi and cellular data can also clear mobile-specific Error 100 cases, because some corporate Wi-Fi networks block the ADP authentication endpoints. Try signing in over cellular data to test.

Contact ADP Customer Support

If you have worked through every solution above and Error 100 persists, the next step is to contact ADP support directly. For employee-level issues, your first call should still be to your company’s HR or payroll administrator, because they can often resolve the issue faster than ADP support and have access to the same admin tools.

If you must contact ADP directly, gather the following information before reaching out. Your company name, your ADP system ID or company code, your employee ID, the exact text of the error, and the list of troubleshooting steps you have already tried. Having this information ready shortens the support call considerably.

Visit the official ADP Contact Us page at adp.com/contact-us to find the right support number or chat option for your product. Employees should select the Administrators and Employees category, while practitioners and enterprise admins should use the practitioner support channel. Phone support is available during business hours for most products, and the live chat option is available for many account types.

Reddit users consistently note that ADP support response times can be slow for non-urgent tickets. If your issue is blocking payroll or pay statement access, mention this urgency when you open the ticket, because escalation paths exist for time-sensitive payroll issues. Enterprise SSO and SAML configuration tickets often require an ADP representative to make back-end changes, so be prepared to coordinate between your IT team and ADP’s support engineering group.

ADP Error Code 100 vs Other ADP Error Codes

ADP uses a numbered error code system to categorize login and account problems. Understanding the difference helps you apply the right fix without wasting time on solutions that target a different error.

• Error 100 is an access-denied or account-configuration error. It is the most common ADP login error and is addressed by the solutions in this guide.
• Error 500 typically indicates a server-side issue on ADP’s end. If you see Error 500, check the ADP service status page and wait for resolution, because the problem is not something you can fix from your device.
• Browser-specific session errors usually point to cookie or JavaScript problems and are resolved by the cache, cookie, and extension steps above.
• Registration errors appear when a new hire tries to register before the employer has fully provisioned the account. Contact HR to confirm the registration code and account setup.

If the error code on your screen is not 100, match it against ADP’s official support documentation or contact ADP support for code-specific guidance.

Frequently Asked Questions

Conclusion

ADP Error Code 100 is frustrating precisely because the message itself tells you nothing actionable. In practice, though, the cause almost always falls into one of four buckets: a locked account, a credential problem, a browser or device issue, or an enterprise SSO misconfiguration. Work through the solutions in this guide in order, starting with a quick call or message to your HR or payroll administrator, because that single step resolves more Error 100 cases than every other fix combined.

If your administrator confirms the account is fine, move on to the password reset, cache clearing, browser update, and extension checks. New hires and SSO users should pay special attention to the Okta, SAML, and Active Directory sections, because a missing employee number in AD is the most commonly overlooked root cause. Mobile users should update the ADP Mobile Solutions app, clear the app cache, and confirm the account is provisioned for mobile access before escalating.

For cases that resist every fix on this page, ADP Customer Support is the final escalation path. Have your company code, employee ID, and a list of attempted fixes ready to shorten the call. Whether you are an employee trying to view a pay stub, a new hire setting up direct deposit, or an IT administrator debugging a SAML integration, the steps above cover how to fix ADP Error Code 100 in 2026 from every angle.