> ## Documentation Index
> Fetch the complete documentation index at: https://docs.derekdinh.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Common IT Error Codes and Windows Update Reference
> A comprehensive reference of Windows system, update, Microsoft 365, Azure AD, OneDrive, and network error codes with recommended actions.
Error codes are your first clue when troubleshooting a technology failure. Rather than searching the internet each time an unfamiliar code appears, use this reference to quickly identify the category of problem and the recommended starting point for resolution. The tables below cover the most frequently encountered error codes across Windows, Microsoft 365, Azure AD (Entra ID), OneDrive, and network diagnostics.
## Windows System Errors
These error codes appear in Windows Event Viewer, application crash dialogs, Blue Screen of Death (BSOD) stop codes, and system logs.
| Error Code | Description | Recommended Action |
| ------------ | ---------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------- |
| `0x00000050` | PAGE\_FAULT\_IN\_NONPAGED\_AREA — A process attempted to access a non-paged memory area | Run `sfc /scannow`; check for faulty RAM with Windows Memory Diagnostic; update or roll back drivers |
| `0x0000007E` | SYSTEM\_THREAD\_EXCEPTION\_NOT\_HANDLED — A system thread generated an exception the error handler did not catch | Identify the faulting driver in the minidump file using WinDbg or WhoCrashed; update or remove the driver |
| `0x0000007F` | UNEXPECTED\_KERNEL\_MODE\_TRAP — Hardware failure or incompatible software | Run hardware diagnostics; check for overheating; test RAM |
| `0x00000024` | NTFS\_FILE\_SYSTEM — NTFS file system driver encountered a fatal error | Run `chkdsk /r` on the affected drive; check disk health with CrystalDiskInfo or `smartctl` |
| `0x0000003B` | SYSTEM\_SERVICE\_EXCEPTION — System service threw an exception | Update all drivers, especially GPU and antivirus; check Event Viewer for faulting module |
| `0x000000D1` | DRIVER\_IRQL\_NOT\_LESS\_OR\_EQUAL — Driver accessed memory at IRQL too high | Identify faulting driver via minidump; update or roll back network, storage, or GPU drivers |
| `0xC0000005` | Access Violation — Program tried to access memory it does not have permission for | Reinstall the application; run `sfc /scannow`; check for malware |
| `0xC0000034` | File not found or object path not found during boot | Run Startup Repair from Windows Recovery Environment; rebuild BCD with `bootrec /rebuildbcd` |
| `0xC000021A` | Windows logon process failed — critical system process terminated | Boot to Safe Mode; run `sfc /scannow` and DISM repair commands |
| `0x80070002` | The system cannot find the file specified | Verify the referenced file or registry key exists; re-run the installer if app-related |
| `0x80070005` | Access Denied — insufficient permissions | Run as administrator; check file/folder ACLs; check UAC settings |
| `0x8007045D` | The request could not be performed because of an I/O device error | Check disk health; reseat or replace SATA/NVMe cable; test with another port |
***
## Windows Update Errors
These codes appear in **Settings → Windows Update** or in the Windows Update log (`%windir%\WindowsUpdate.log` or via `Get-WindowsUpdateLog` in PowerShell).
| Error Code | Description | Recommended Action |
| ------------ | --------------------------------------------------------- | ------------------------------------------------------------------------------------------------------ |
| `0x80070002` | File not found — update components are damaged | Run `sfc /scannow`; run the Windows Update troubleshooter; reset the Windows Update service components |
| `0x80070003` | Path not found — update staging directory issue | Reset Windows Update components; clear the SoftwareDistribution folder |
| `0x8007000D` | Invalid data — update file is corrupt | Delete contents of `C:\Windows\SoftwareDistribution\Download` and retry |
| `0x800705B4` | Timeout — Windows Update service timed out | Check internet connectivity; restart Windows Update service; disable VPN/proxy temporarily |
| `0x80073701` | Missing assembly — manifest references a file not present | Run DISM: `DISM /Online /Cleanup-Image /RestoreHealth` |
| `0x8024401C` | WSUS server unreachable | Verify WSUS server URL in Group Policy; check proxy settings; test connectivity to WSUS server |
| `0x80244022` | HTTP 503 — WSUS/Windows Update server busy | Retry later; check WSUS server health and disk space |
| `0x80240034` | Update not applicable to this machine | Confirm the update is compatible with the installed Windows version and architecture |
| `0x80070570` | File or directory is corrupt and unreadable | Run `chkdsk /r`; run `sfc /scannow`; consider in-place OS repair |
| `0x800F0922` | CBS update failure — rollback occurred | Check CBS log at `C:\Windows\Logs\CBS\CBS.log` for the specific component failure; run DISM |
| `0x80092004` | Cannot find object or property — certificate store issue | Run Windows Update troubleshooter; check system date and time are correct |
| `0xC1900101` | Feature Update driver incompatibility | Run the Windows 11 PC Health Check; update all drivers before reattempting the upgrade |
| `0xC1900200` | Device does not meet minimum requirements for the upgrade | Verify hardware meets requirements; check TPM 2.0 and Secure Boot status |
To reset Windows Update components manually, stop the `wuauserv`, `cryptSvc`, `bits`, and `msiserver` services, rename the `SoftwareDistribution` and `Catroot2` folders, then restart the services. Microsoft provides a script for this process at `https://support.microsoft.com/en-us/topic/fix-windows-update-errors-18b693b5-7818-5825-8a7e-2a4a37d6d787`.
***
## Microsoft 365 / Azure AD Errors (AADSTS Codes)
AADSTS codes appear on the Microsoft sign-in error page and in Azure AD sign-in logs. They provide precise identification of authentication and authorisation failures.
| Error Code | Description | Recommended Action |
| -------------- | ----------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------- |
| `AADSTS50020` | User account from an external identity provider does not exist in the tenant, or guest user has not accepted invitation | Send a new B2B guest invitation; verify the user's account type in Azure AD |
| `AADSTS50034` | User account does not exist in the directory | Verify the UPN is correct; check whether the user was accidentally deleted; restore from Deleted Users |
| `AADSTS50053` | Account locked due to Smart Lockout (too many failed sign-in attempts) | Wait for the lockout period to expire (up to 30 seconds to 5 minutes); reset the password; review for brute-force activity |
| `AADSTS50057` | User account is disabled | Enable the account in Azure AD admin centre → Users |
| `AADSTS50076` | MFA is required but the user has not registered | Register the user's MFA methods at `https://aka.ms/mfasetup` |
| `AADSTS50105` | User is not assigned to the application | Assign the user or user's group to the application in Enterprise Applications → User and group assignments |
| `AADSTS50126` | Invalid username or password / credentials invalid | Reset the user's password; clear cached credentials; check for smart lockout |
| `AADSTS50128` | Invalid domain name / tenant identifier not found | Verify the domain is added and verified in the tenant; check the UPN suffix |
| `AADSTS50131` | Conditional Access – device compliance required | Enrol device in Intune; check compliance policy status in the Intune admin centre |
| `AADSTS65001` | User or administrator has not consented to the application | Grant admin consent in Azure AD → Enterprise Applications → Permissions |
| `AADSTS700016` | Application not found in the tenant | Register or add the application to the tenant via Enterprise Applications |
| `AADSTS70011` | Invalid scope — the requested OAuth scope is not valid for this app | Update the application's API permissions registration; check requested scopes in the app's authentication flow |
| `AADSTS90072` | User account does not exist in the tenant | Check the UPN; ensure the user's account was not deleted; check for domain federation issues |
***
## OneDrive Sync Errors
OneDrive displays these error codes in the sync error panel and in the application event log.
| Error Code | Description | Recommended Action | |
| ------------ | ------------------------------------------------------------------------ | ----------------------------------------------------------------------------------------------------------- | --- |
| `0x8007016A` | Cloud file provider is not running | Restart OneDrive; restart the Windows Storage Service (`StorSvc`) | |
| `0x80070194` | Cloud file provider exited unexpectedly | Close applications accessing the file; restart OneDrive; reset OneDrive if persistent | |
| `0x80070005` | Access denied — insufficient permissions on the local file | Take ownership of the file; check folder permissions; close programs with file locks | |
| `0x8007007B` | Invalid file name — unsupported characters or path | Rename the file to remove unsupported characters (\`\* : \< > ? / \\ | \`) |
| `0x800700DE` | File type not allowed by server policy | Check SharePoint library's allowed file types; rename or convert the file | |
| `0x80071129` | The tag present in the reparse point buffer is invalid | Delete and re-create the OneDrive sync connection; check for symbolic links or junctions in the sync folder | |
| `0x8004DA9A` | You need to sign in | Sign into OneDrive again via the system tray icon | |
| `0x8004DE40` | OneDrive cannot connect to the service | Check internet connectivity; verify proxy settings; check firewall rules for `onedrive.live.com` | |
| `0x8004DE86` | This file can't be synced because another version of OneDrive is running | Sign out of personal OneDrive if using OneDrive for Business, or resolve account conflict | |
| `0x80070570` | File or directory is corrupt and unreadable | Run `chkdsk /r` on the local drive; try copying the file to a different location and re-uploading | |
***
## Network Errors
These codes appear in browser messages, Windows network diagnostics, application logs, and command-line tools.
| Error Code | Description | Recommended Action |
| ----------------------------- | --------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------- |
| `0x80070035` | The network path was not found (accessing SMB share) | Verify the server name is correct; check DNS resolution with `nslookup`; confirm SMB/port 445 is open |
| `0x80004005` | Unspecified network error — access denied or path unavailable | Check share and NTFS permissions; verify the user's credentials are valid for the resource |
| `DNS_PROBE_FINISHED_NXDOMAIN` | DNS cannot resolve the domain name | Check DNS server settings; flush DNS cache (`ipconfig /flushdns`); verify the domain name |
| `ERR_CONNECTION_TIMED_OUT` | Browser could not reach the server within the timeout period | Check network connectivity; verify firewall rules; test with `ping` and `tracert` |
| `ERR_SSL_PROTOCOL_ERROR` | SSL/TLS handshake failed | Check system date and time; clear SSL state (Internet Options → Content → Clear SSL State); update browser |
| `ERR_CERT_AUTHORITY_INVALID` | Browser does not trust the site's SSL certificate | Check if the certificate is self-signed; check if a proxy is intercepting SSL (SSL inspection); verify the certificate chain |
| `504 Gateway Timeout` | Upstream server did not respond in time | Check the health of the origin server; check proxy or load balancer timeouts; review server logs |
| `503 Service Unavailable` | Server temporarily unable to handle requests (overloaded or in maintenance) | Wait and retry; check server resource utilisation (CPU/RAM); check application pool state |
| `401 Unauthorized` | Authentication required or credentials rejected | Verify credentials; check if the account is locked; review authentication configuration |
| `403 Forbidden` | Server understood the request but refuses to authorise it | Check user permissions and ACLs; review IP allowlist/blocklist rules; check web application firewall rules |
When escalating any error code to Microsoft Support or your vendor, always provide the full error code including any prefix (e.g., `0x` for Windows hex codes, `AADSTS` for Azure AD), the application or service where it appeared, the timestamp, and any available Correlation ID or Request ID.