Error 0x6D9: Replication Service Not Running - Fix Guide 2025

Log Name:      Application
Source:        MSExchangeRepl
Event ID:      3355
Level:         Error
Description:   The Microsoft Exchange Replication service failed to
               communicate with server 'EXCH02.company.com'.
               Error: 0x6D9 (There are no more endpoints available
               from the endpoint mapper)

# On the affected server, run as Administrator
Restart-Service MSExchangeRepl -Force

# Verify service started
Get-Service MSExchangeRepl | Format-List Name,Status,StartType

# Check replication resumed
Start-Sleep -Seconds 30
Get-MailboxDatabaseCopyStatus -Server $env:COMPUTERNAME |
    Format-Table DatabaseName,Status,CopyQueueLength

# Check service account
$svc = Get-WmiObject Win32_Service -Filter "Name='MSExchangeRepl'"
$svc.StartName  # Should be LocalSystem or specific service account

# Reset service to LocalSystem if needed
sc.exe config MSExchangeRepl obj= LocalSystem

# Check for dependency issues
sc.exe qc MSExchangeRepl

# Restart with dependencies
Restart-Service RpcSs -Force
Start-Sleep -Seconds 5
Start-Service MSExchangeRepl

# If still fails, check for corrupted service registration
# Re-register Exchange services
cd "C:\Program Files\Microsoft\Exchange Server\V15\Bin"
.\ServiceControl.ps1 -Action Start -ServiceName MSExchangeRepl

# Reset RPC endpoint mapper
Restart-Service RpcSs -Force
Start-Sleep -Seconds 10

# Re-register all Exchange RPC endpoints
Get-Service MSExchange* | Where-Object {$_.Status -eq "Running"} | Restart-Service -Force

# Verify RPC endpoints registered
netsh rpc show int  # Should list Exchange interfaces

# Check Windows Firewall isn't blocking RPC
Get-NetFirewallRule -DisplayGroup "Remote*" | Where-Object {$_.Enabled -eq $true} |
    Format-Table DisplayName,Enabled,Direction

# Required ports for DAG replication
$requiredPorts = @(135, 64327, 64328, 64329)  # RPC, Replication

# Test to each DAG member
$dagMembers = (Get-DatabaseAvailabilityGroup).Servers
foreach ($server in $dagMembers) {
    Write-Host "Testing $server :" -ForegroundColor Cyan
    foreach ($port in $requiredPorts) {
        $test = Test-NetConnection -ComputerName $server -Port $port -WarningAction SilentlyContinue
        "$port : $($test.TcpTestSucceeded)"$test.TcpTestSucceeded)"
    }
}

# Open firewall rules if needed
New-NetFirewallRule -DisplayName "Exchange Replication" -Direction Inbound -LocalPort 64327-64329 -Protocol TCP -Action Allow

# Check for memory issues
Get-Counter '\Process(msexchangerepl)\Working Set - Private' -SampleInterval 5 -MaxSamples 3

# Check crash dumps
Get-ChildItem "C:\Program Files\Microsoft\Exchange Server\V15\Logging\Diagnostics\DailyPerformanceLogs" -Filter "*.csv" |
    Sort-Object LastWriteTime -Descending | Select-Object -First 1

# Increase service recovery options
sc.exe failure MSExchangeRepl reset= 86400 actions= restart/60000/restart/60000/restart/60000

# Check for antivirus interference
# Ensure AV excludes: C:\Program Files\Microsoft\Exchange Server\V15\*

# 1. Verify service running
Get-Service MSExchangeRepl | Format-List Name,Status

# 2. Check replication health
Test-ReplicationHealth | Format-Table Server,Check,Result -AutoSize

# 3. Verify database copies healthy
Get-MailboxDatabaseCopyStatus * | Format-Table DatabaseName,MailboxServer,Status,CopyQueueLength

# 4. Test failover capability (optional)
# Test-MailboxDatabaseFailover -DatabaseCopyName "DB01\EXCH02"-DatabaseCopyName "DB01\EXCH02"

# 5. Monitor for new errors
Get-EventLog -LogName Application -Source MSExchangeRepl -Newest 10 |
    Where-Object {$_.EntryType -eq "Error"}

# Configure service to restart automatically on failure
sc.exe failure MSExchangeRepl reset= 86400 actions= restart/30000/restart/60000/restart/120000

# Verify configuration
sc.exe qfailure MSExchangeRepl

# Add to scheduled task (every 5 minutes)
$servers = (Get-DatabaseAvailabilityGroup).Servers
$stoppedServices = @()

foreach ($server in $servers) {
    $svc = Get-Service -ComputerName $server -Name MSExchangeRepl -ErrorAction SilentlyContinue
    if ($svc.Status -ne "Running") {
        $stoppedServices += "$server : $($svc.Status)"$svc.Status)"
    }
}

if ($stoppedServices) {
    Send-MailMessage -To "admin@company.com" -Subject "Exchange Replication Service Alert" -Body ($stoppedServices -join [Environment]::NewLine) -SmtpServer "mail.company.com"
}