Common IT Error Codes and Windows Update Reference - IT Troubleshooting Knowledge Base

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.

​Windows System Errors

​Windows Update Errors

​Microsoft 365 / Azure AD Errors (AADSTS Codes)

​OneDrive Sync Errors

​Network Errors

Windows System Errors

Windows Update Errors

Microsoft 365 / Azure AD Errors (AADSTS Codes)

OneDrive Sync Errors

Network Errors