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Practical articles from our teams.

186 articles

[ KB-AD-001 · Windows Server & AD ]

AD user cannot sign in

Symptoms
account lockout
Problem
AD user cannot sign in.
Likely causes
Bad passwords cached in services, mapped drives or devices.
Quick fix
Check domain controller lockout events and originating host; fix stored credentials and verify account security.
Microsoft documentation

[ KB-AD-002 · Windows Server & AD ]

AD replication failing

Symptoms
replication error, stale accounts
Problem
AD replication failing.
Likely causes
DNS, RPC connectivity, site topology or lingering issue.
Quick fix
Run repadmin /replsummary and /showrepl; inspect DNS, network and replication error before remediation.
Microsoft documentation

[ KB-AD-003 · Windows Server & AD ]

Group Policy not applying

Symptoms
gpupdate ineffective
Problem
Group Policy not applying.
Likely causes
OU scope, security filtering, WMI filter or SYSVOL.
Quick fix
Run gpresult /h; check inheritance, security filtering, SYSVOL access and related event logs.
Microsoft documentation

[ KB-AD-004 · Windows Server & AD ]

Domain controller DNS errors

Symptoms
SRV lookup failed
Problem
Domain controller DNS errors.
Likely causes
AD DNS zone or forwarder issue.
Quick fix
Check AD-integrated DNS health, SRV registration and client DNS settings; run dcdiag /test:dns.
Microsoft documentation

[ KB-AD-005 · Windows Server & AD ]

Kerberos logon fails

Symptoms
KRB_AP_ERR_SKEW
Problem
Kerberos logon fails.
Likely causes
Excessive clock difference.
Quick fix
Verify domain time hierarchy and NTP on client/DC; synchronize trusted time.
Microsoft documentation

[ KB-AD-006 · Windows Server & AD ]

SYSVOL not replicating

Symptoms
group policies missing
Problem
SYSVOL not replicating.
Likely causes
DFSR backlog or replication fault.
Quick fix
Review DFS Replication event logs and backlog; troubleshoot DFSR health; do not casually delete SYSVOL contents.
Microsoft documentation

[ KB-AD-007 · Windows Server & AD ]

File share access denied

Symptoms
permissions error
Problem
File share access denied.
Likely causes
NTFS/share ACL or group membership.
Quick fix
Check effective NTFS and share permissions and token refresh; apply least privilege.
Microsoft documentation

[ KB-AD-008 · Windows Server & AD ]

Server disk space exhausted

Symptoms
server volume full
Problem
Server disk space exhausted.
Likely causes
Logs, shadow copies or data growth.
Quick fix
Determine growth source; remove only approved disposable files, revise retention and expand storage if needed.
Microsoft documentation

[ KB-AD-009 · Windows Server & AD ]

DNS record changes not reflected

Symptoms
old IP resolved
Problem
DNS record changes not reflected.
Likely causes
TTL/cache or nonauthoritative server.
Quick fix
Query authoritative DNS and client resolver; correct record and wait for TTL or flush targeted caches.
Microsoft documentation

[ KB-AD-010 · Windows Server & AD ]

DHCP clients not receiving IP addresses

Symptoms
APIPA 169.254 address
Problem
DHCP clients not receiving IP addresses.
Likely causes
Scope exhausted, relay or service problem.
Quick fix
Verify scope capacity, DHCP server authorization/service and relay path; renew client lease after fixing.
Microsoft documentation

[ KB-AD-011 · Windows Server & AD ]

Domain trust broken

Symptoms
trust relationship failed
Problem
Domain trust broken.
Likely causes
Computer password mismatch or connectivity.
Quick fix
Check DNS and DC reachability; repair secure channel using supported administrative method.
Microsoft documentation

[ KB-AD-012 · Windows Server & AD ]

Windows Server backup fails

Symptoms
backup error
Problem
Windows Server backup fails.
Likely causes
VSS writers, target capacity or access.
Quick fix
Inspect backup logs and vssadmin list writers; fix faulty writer/space and retry; verify restore points.
Microsoft documentation

[ KB-AD-013 · Windows Server & AD ]

Hyper-V VM will not start

Symptoms
failed to start VM
Problem
Hyper-V VM will not start.
Likely causes
Storage path, hypervisor or resource contention.
Quick fix
Read VMMS event logs; check VHDX accessibility, host capacity and checkpoints; avoid deleting disks.
Microsoft documentation

[ KB-AD-014 · Windows Server & AD ]

Remote Desktop Services licensing alert

Symptoms
grace period expired
Problem
Remote Desktop Services licensing alert.
Likely causes
RDS CAL server/mode configuration.
Quick fix
Verify licensing server, CAL availability and collection licensing mode; configure compliant licensing.
Microsoft documentation

[ KB-AZAPP-001 · Azure App Service ]

App Service returns HTTP 500

Symptoms
internal server error
Problem
App Service returns HTTP 500.
Likely causes
App exception, missing setting or dependency.
Quick fix
Review application logs, exceptions and recent deployments; verify app settings and downstream connections; roll back faulty release.
Microsoft documentation

[ KB-AZAPP-002 · Azure App Service ]

App Service returns HTTP 502 or 503

Symptoms
bad gateway, service unavailable
Problem
App Service returns HTTP 502 or 503.
Likely causes
Process crash, worker health or overload.
Quick fix
Open Diagnose and Solve Problems; inspect health checks, logs and memory; restart only if appropriate, then fix underlying failure.
Microsoft documentation

[ KB-AZAPP-003 · Azure App Service ]

App Service deployment succeeds but old site shows

Symptoms
stale content, old version
Problem
App Service deployment succeeds but old site shows.
Likely causes
Wrong deployment slot, cache or artifact path.
Quick fix
Verify target slot, deployment logs, startup command and CDN/browser cache; confirm deployed build/version.
Microsoft documentation

[ KB-AZAPP-004 · Azure App Service ]

App Service fails to start after deployment

Symptoms
container startup failure
Problem
App Service fails to start after deployment.
Likely causes
Incorrect startup command, port or missing environment variable.
Quick fix
Review container/runtime logs and health; validate startup command, WEBSITES_PORT where relevant and configuration.
Microsoft documentation

[ KB-AZAPP-005 · Azure App Service ]

Custom domain verification fails

Symptoms
domain ownership failed
Problem
Custom domain verification fails.
Likely causes
Missing DNS TXT/CNAME records or propagation.
Quick fix
Confirm expected domain-validation records with DNS lookup; correct host name and allow propagation.
Microsoft documentation

[ KB-AZAPP-006 · Azure App Service ]

App Service TLS certificate not binding

Symptoms
HTTPS warning, certificate missing
Problem
App Service TLS certificate not binding.
Likely causes
Certificate expired or domain/hostname mismatch.
Quick fix
Validate DNS, certificate validity and hostname binding; renew and bind correct cert without disabling HTTPS.
Microsoft documentation

[ KB-AZAPP-007 · Azure App Service ]

App Service cannot reach database

Symptoms
connection timeout
Problem
App Service cannot reach database.
Likely causes
Firewall, VNet integration, DNS or credentials.
Quick fix
Test name resolution and port from app; verify VNet/private endpoint rules, identity and connection settings.
Microsoft documentation

[ KB-AZAPP-008 · Azure App Service ]

App Service managed identity access denied

Symptoms
403 from Key Vault or Storage
Problem
App Service managed identity access denied.
Likely causes
Identity not enabled or missing roles.
Quick fix
Confirm system/user-assigned identity and target scope; assign minimum necessary data-plane permission; account for propagation.
Microsoft documentation

[ KB-AZAPP-009 · Azure App Service ]

App Service cold start slow

Symptoms
first request slow
Problem
App Service cold start slow.
Likely causes
Idle worker or heavy startup.
Quick fix
Use supported Always On plan/settings or optimize startup; evaluate scale and health check.
Microsoft documentation

[ KB-AZAPP-010 · Azure App Service ]

App Service scaling not helping

Symptoms
high latency with more instances
Problem
App Service scaling not helping.
Likely causes
DB bottleneck, sticky sessions or shared external limit.
Quick fix
Inspect per-instance and dependency metrics; fix downstream limits and session state before scaling more.
Microsoft documentation