Common ThinManager problems on the plant floor and what to check, area by area. Every status, menu, wizard page and page number comes from the Rockwell user manual
Safety: a Restart or Reboot of a terminal, or a restart of a Remote Desktop Server or the ThinServer service, can blank operator screens on a running line. Follow the plant's permit rules and warn operations first.
1. Read the ThinManager tree icons first
| Icon | What the manual says it means | What to check |
|---|---|---|
| Red ThinManager Server | The console is not talking to the ThinServer ( |
Right-click, "Reconnect"; the ThinServer service in Windows Services (p. 93) |
| "Yellow Monitor" | Terminal is booting (p. 42) | Stuck here: section 2 |
| "Red Monitor" | Terminal is off or cannot communicate with the server | Power, cable, section 2 |
| "Red X" | Disabled with "Tools > Disable"; shows a splash screen while the session keeps running on the RDS (pp. 37, 42) | "Tools > Enable" |
| "Exclamation Mark" | A configuration change needs a restart | "Tools > Restart" when permitted |
| Red lightning bolt | A defined connection that is not active (p. 47) | Sections 3 and 4 |
Terminal missing from the tree: "View > Show Connected Only" hides unpowered or unconnected thin clients (p. 37). "Tools > Restart" resends the configuration; "Tools > Reboot" cycles the terminal's power and reloads firmware and configuration; "Reboot Server" ends every session on the RDS abruptly (p. 36).
2. Thin client does not boot or get its configuration
A ThinManager-ready thin client has the ThinManager BIOS and uses DHCP or a static IP. A ThinManager-compatible one lacks it, stores no static IP and needs DHCP and PXE (p. 346).
| Symptom | What the manual says | What to check |
|---|---|---|
| ThinManager-ready gets a DHCP address but never reaches the server | The server address comes from Option 066 "Boot Server Host Name" (pp. 347–348) | Option 066 = ThinManager Server IP; or press the space bar at boot, open the "IP Configuration Menu", set (B) Primary and (C) Secondary ThinManager Server; with DHCP kept for the terminal IP this needs Boot Loader 5.01 or later (pp. 349–351) |
| "A Device Exists on the Network with this Terminal's IP Address…" | Duplicate static IP; firmware download stops (p. 351) | Correct the IP, reboot |
| ThinManager-compatible does not PXE boot | "Enable PXE Server" in "Manage > PXE Server", right mode (pp. 355–356); with "Allow New PXE Clients" cleared only known clients are answered (p. 357) | Mode table below |
| A new terminal cannot join | Clearing "Allow unknown terminals to connect" blocks new terminals and replacements (p. 698) | ThinManager Server Configuration Wizard |
| Terminal stops at authentication | Device Authentication (firmware 13.2.0 or later) asks for Windows credentials on first connection; if it fails the terminal does not boot (pp. 700–701) | Account with "Allow Terminal Replacement" permission |
PXE modes (pp. 355–361):
| Mode | Client IP from | ThinManager IP, boot file | Note |
|---|---|---|---|
| "Using standard DHCP server" | Existing DHCP | ThinManager | Easiest (p. 358) |
| "Using standard DHCP server on this machine" | DHCP on the ThinManager computer | ThinManager | Open UDP 4011, also for UEFI boot (p. 359) |
| "Using standard DHCP server with Boot Options (PXE Disabled)" | DHCP | Option 066 = ThinManager IP, Option 067 = acpboot.bin | Redundant pair: both IPs separated by a space (p. 360) |
| "Not using standard DHCP server" | ThinManager IP range | ThinManager | Not a true DHCP server; serves PXE devices only (pp. 361, 368) |
Allow the ports on pp. 24–25 through firewalls, e.g. UDP 67, UDP 69, UDP 4900, TCP 2031 (configuration), TCP 3389, TCP 8443. Firmware goes over HTTPS by default; if blocked, the server tries TFTP when "Enable TFTP" is checked (pp. 723–724). Keep one PXE server per network (p. 25). See also FactoryTalk / Logix firewall ports.
3. Remote Desktop Server shown red or gray
Highlight "RDS Servers" in the Display Servers tree and open the "Status" tab (p. 91).
| Colour | "Value" on the Status tab | Meaning | Fix from "Solutions to Failed or No Connection" |
|---|---|---|---|
| Green | "OK" | ThinServer reads the server with the administrative account | — |
| Gray | "No login information supplied" | Administrative account left blank | Remote Desktop Server Wizard, "Remote Desktop Server Name" page: enter an account in "Log In Information" |
| Red | "User specified does not have permission to connect" | Administrative account failed | Correct the account there |
| Red | "The RPC Server is unavailable" or "WTSAPI32.dll failed" | Server offline or missing the Terminal Services/Remote Desktop Protocol role | Server and role |
Table source: p. 92. Red or gray does not mean terminals cannot log in; it only shows whether ThinManager can read the server's resources (p. 92). If large domains time out before the domain controller validates the user, set the ThinServer service to log on with a local administrative account ("Log On" tab) and restart it (pp. 92–94).
4. Display client not starting, failover not switching
| Symptom | What the manual says | What to check |
|---|---|---|
| A login screen instead of the application | No valid Windows account in the terminal configuration gives an NLA login screen (p. 26); clearing "Allow Auto-Login" forces manual login (p. 174) | One unique Windows account per terminal (p. 313), in Remote Desktop Users (p. 73) |
| Main RDS fails, terminal does not switch | Needs two or more RDS in "Selected Remote Desktop Servers" ("Display Client Members" page), same applications in identical locations, same Windows accounts (pp. 189–190) | Compare both servers |
| Switching is slow | "Monitoring Configuration" page: "Fast" takes 10…20 s, then the application loads (pp. 191–192) | Instant Failover |
| Instant Failover has no backup session | Check "Instant Failover" on the "Remote Desktop Services and Workstation Options" page; Instant Failover is free for ThinManager but needs a second application license, because two sessions run the application (pp. 165, 192–193); the per-terminal Instant Failover license on p. 667 is stated for the legacy Instant Failover Module | Green plus yellow bolt = two sessions (p. 47) |
| No return to the main RDS after recovery | "Enforce Primary" makes the terminal switch back when the primary RDS is available again; "Primary Up Delay" holds the return until that server is ready (pp. 188, 192) | Display client options |
To test failover in an approved window, "Tools > Disable" an RDS, then "Tools > Enable" (pp. 94–95). HMI application faults: see FactoryTalk View SE client cannot connect and SCADA server redundancy.
5. Licensing
| Situation | What the manual says | What to check |
|---|---|---|
| Unsure which license type is used | Two modes: ThinManager Master License and FactoryTalk Activations (p. 53) | "Install > License Mode" |
| Master License | The Product License gives terminals permission to connect and sets their features; a synchronized pair shows Primary and Secondary Installation IDs (pp. 53, 61) | "Install > Licenses": "Master License Number", Product Licenses, Installation ID (pp. 61–63) |
| FactoryTalk Activations | Without activation some Rockwell products do not run, run with reduced functions, or stop after a limited time (p. 63) | "Install > Licenses", "Add Activations" (pp. 64–65) |
The manual does not say what a terminal shows when licenses run short; notification settings are under "View > Options" (p. 37).
6. Server pair not synchronized
Highlight the ThinManager Server, open the "Synchronization" tab: "Synchronization State" must read "Synchronized" (p. 57).
| Symptom | What the manual says | What to check |
|---|---|---|
| Synchronization failure after an upgrade or a server replacement | The default installation has no certificate, so upgrades report a synchronization failure; a replaced server may need certificates updated (p. 60) | "Manage TLS Certificates", "ThinManager Server Synchronization"; the partner certificate trusted in the Microsoft Certificate Store |
| Cannot edit on the Secondary | Mirrored Redundancy: only the Primary has the administrative console; terminals can still boot from the Secondary (p. 54) | Edit on the Primary; mirrored requires Automatic Synchronization (p. 58) |
| Terminals do not move to the Secondary | The terminal needs the Secondary IP: entry (C) in the IP Configuration Menu, or both IPs in Option 066 (pp. 349, 360) | Thin client, DHCP |
7. Logs, shadow and what to record
- Event Log: "Historical Logging" page of the ThinManager Server Configuration Wizard sets "Maintain Event Log for X days" and "Choose events to log"; Remote Desktop Server and ThinManager User events are off by default (pp. 704–705). Read the "Event Log" tab of a terminal or server; double-click an event for "Event Details" (pp. 705, 707). "Tools > Clear" erases it (p. 37), so record first.
- Shadow: view a terminal from the console; clear "Interactive" for view-only (p. 38). The "ThinManager Web Browser User Interface" is a read-only console with terminal status, event log and shadow, once "Web Client Endpoints" is enabled (pp. 48–51).
Before calling for support, record:
- Version and build ("Help > About", p. 39) and firmware package ("Versions" tab, p. 660).
- Terminal name, model, MAC, IP, icon colour, a photo of the screen message.
- RDS colour and "Value" text; "Synchronization State"; License Mode.
- Event Log entries, time of fault, what was restarted; a configuration backup ("Manage > Backup", p. 19).
Need an engineer at the plant: request support.
Frequently asked questions
Does a red Remote Desktop Server in ThinManager mean thin clients lost their connection?
Not necessarily. Red or gray only shows whether ThinManager can read the server's resources; terminals may still run (
What should I check when a ThinManager thin client will not PXE boot?
Check "Enable PXE Server", the PXE mode, and "Allow New PXE Clients" for a new unit (pp. 355–357). With DHCP Boot Options, Option 066 is the ThinManager IP and Option 067 is acpboot.bin (p. 360).
How do I know two ThinManager Servers are synchronized?
Open the "Synchronization" tab of the ThinManager Server; "Synchronization State" must read "Synchronized" (p. 57). A failure after an upgrade can come from a missing TLS certificate (p. 60).
Where are ThinManager error logs?
On the "Event Log" tab of a terminal or server; double-click an event for details (pp. 705, 707). Events to log and retention days are set on the "Historical Logging" page (p. 704).
Sources
- Rockwell Automation,
TM-UM001L-EN-P , ThinManager – Thin Client Management Platform User Manual (version 14.02.00), 07/2026 — pp. 19, 24–26, 36–39, 41–42, 47–51, 53–54, 57–58, 60–65, 73, 91–95, 165, 174, 188–193, 313, 346–351, 355–361, 368, 660, 667, 698–707, 723–724
Read 8 November 2026. This article paraphrases the sources and does not quote them; read the original documents before designing or working on a system.