troubleshooting

A repeatable MS/TP troubleshooting flow using multimeter checks, termination verification, topology fixes, and fast isolation by bifurcation.

Decision-tree troubleshooting for Niagara TLS failures, covering trust stores, certificate lifecycle, and fox/foxs/foxwss port mismatches.

Best-practice workflow for maintaining SCT archives using site discovery, backups, validation cadences, and a recovery playbook.

Commissioning and troubleshooting checklist for analog scaling with practical formulas, meter-first validation, and thermistor curve gotchas.

Comprehensive guide to managing the Metasys SQL Server Express database, including backup scheduling, restore procedures, purging, and handling the 10 GB size limit.

Standardized point-to-point commissioning procedure for BAS projects covering physical I/O verification, controller checkout, and functional testing documentation.

Practical field guide for backing up and restoring Niagara stations on JACE controllers, covering USB procedures, Workbench backups, platform recovery, and common pitfalls.

Troubleshooting guide for configuring 4-20mA sensors on Distech APEX UIO controllers, including common issues with Trend T/PI sensors and proper scaling setup.

Troubleshooting guide for Carrier SystemVU controllers that lose configuration after power cycles, covering EEPROM failures, firmware issues, and workarounds.

Resolving Java-related browser issues when connecting to Niagara systems, including plugin deprecation, version compatibility, and migration to HTML5.

Troubleshooting virtual Px graphics issues in multi-site Niagara deployments, particularly alarm console components that break when moved from JACEs to Supervisor.

Troubleshooting guide for integrating Carel pCO3 and pCO5+ controllers via pCONet cards in Xetex Makeup Air Units.

Configuration guidance for setting up a new MSTP FLN (Field Level Network) on a Siemens PXC100 controller via telnet.

Troubleshooting guide for NaN errors on Johnson Controls AHU setpoints in Niagara-based BMS systems.

Troubleshooting guide for restoring software functionality on Distech ECY-APEX controllers following a factory reset.

Comprehensive troubleshooting and configuration guide for Alerton BACtalk and IBEX building automation systems.

Troubleshooting guide for missing JAR modules when using Honeywell WEBs-N4 Workbench with Distech JACEs.

Comprehensive guide covering professional-grade troubleshooting of BACnet MS/TP communications including physical layer analysis and network diagnostics.

Procedural guide for commissioning legacy Niagara AX controllers with version mismatches and licensing issues.

Modbus Read Status Error Code 2 in Niagara 4 - Device exception error. The Modbus device returned an exception code...

Error: HTTP status 504: Gateway Timeout in Metasys NAE 10.1 - Add local address ranges to Windows proxy exceptions or use a configuration script.

Modbus Read Status Error Code 1 in Niagara 4 - Communication error. Check network connectivity, verify device address is correct...

Modbus Read Status Error Code 0 in Niagara 4 - Error Code 0 indicates no error. The Modbus device read operation completed successfully.

Error: Internet Information Services (IIS) is not running in Metasys NAE 10.1 - Start World Wide Web Publishing and IIS Admin services; run iisreset if necessary.

BACnet Error Class and Error Code in Niagara AX - When a write operation fails, the write status displays descriptive text in a colon-separated format...

Error: Error creating TFTP server: Address in use in Metasys NAE 10.1 - Ensure Server IP matches computer IP, delete Server IP in defaults, and restart tool.

Error: PostfileTransferError - All retries are exhausted in Metasys NAE 10.1 - Lengthen communication timeouts in the Timeouts tab and restart.

Error: 512MB of Flash Storage is required in Metasys NAE 10.1 - Use hardware with 512 MB memory or contact JCI for upgrade options.

Error: Maximum Retries Exceeded / Communication lost unexpectedly in Metasys NAE 10.1 - Try a PXE Only update on the same switch as the NAE.

Error: IIS is not installed in Metasys NAE 10.1 - Add Internet Information Services (IIS) via Windows Features.

RUN LED is not on steady and PEER COM LED is not off or flickering in Metasys NAE 10.1 - Wait for the Post File Transfer Complete message...

Item Not Found (Focus window) error in Metasys SNC 13.0 - The SNC is unpaired with the Site Director. Re-pair the SNC with the Site Director...

GENL FAULT LED stays on (NAE repeatedly assigned same IP) in Metasys NAE 10.1 - Disable Virtual Private Network (VPN) firewalls.

Unable to Login or Unable to communicate with site director (Pairing error) in Metasys SNC 13.0 - This occurs during NCE to SNC migration...

FAULT LED on (SNC overheats) error in Metasys SNC 13.0 - Verify mounting orientation and installation per instructions. Clear ventilation blockages...

VM (10) error on AAC20 controller - requires firmware reinstall and memory optimization.

VM (45) error - number of kits uploaded exceeds 256 kB memory limit.

VM (43) error - application not properly saved due to power loss or interference.

SNC HEARTBEAT LED blinking abnormally - check power, wiring, and baud rates.

VM (100) error - component placed under wrong network in application.

VM (42) error - application file uploaded to device is damaged.

HTTP 500.21 error in Metasys UI - requires ASP.NET and IIS configuration.

SNC does not operate when powered on - use Recovery button for flash memory issues.

Network engine (NAE, SNC, NIE) does not respond to automatic or manual commands.

Web service fails when ports 80 and 443 are already in use on startup.

Niagara Service/daemon fails to start particularly after uninstall attempts.

JACE 8000 experiencing unexpected reboots due to memory, power, or software issues.

Communication issues between Niagara network sites involving remote buildings.

Unable to discover new JACE on Niagara Network due to license compatibility issues.

Message appears when trying to log in to NxE85 or LCS85 - license required.

Controller Configuration Tool unable to create CCT_DB database though FDB_Control is created.

TLS handshake failed due to certificate issues - wildcard certificates may cause problems.

Error in Station Copier preventing backup operations due to security software.

Maximum of 6000 histories exceeded on JACE-8 causing performance degradation.

Station failed due to Java licensing issue - sunj2se feature not licensed.

Communication failure on MS/TP bus due to addressing or wiring issues.

Error appears when trying to log in to ADS/ADX - device runtime status not determined.

Timeout occurs when Metasys Database Manager attempts to connect to SQL Server database.

Station fails to start due to expired license - renewal required.

High CPU usage leads to performance issues and station instability.

Windows Shell error when saving station information in Application Tunneling dialog.

Supervisor crashes with OutOfMemoryError and Engine Watchdog Timeout Stack Dump.

Engine Watchdog Timeout occurs when Nre:Engine thread becomes unresponsive due to blocking operations.

Station fails to load due to missing or corrupted history extension module.

How to increase Java heap memory allocation on Windows Supervisor station.

Widespread JACE failures caused by Weather Service making station inoperable.

SNC network engine overheating causes FAULT LED and erratic behavior.

Windows startup timeout causes Niagara service and platform daemon to fail to start.

Station killed by daemon due to low system memory despite available RAM.

NullPointerException in MSTP property sheet when setting up BACnet network.

Station appears running but inaccessible due to config.bog.lock issues after upgrade from AX 3.3 to 3.5.

Error code "Write Fault: Property:Write Access Denied" in Niagara N4 - Remap the points as unwriteable or change present value field to 3113.

Connection issues when discovering points from JACE into supervisor.

Web service fails when ports 80/443 are already in use by another application.

Warning unresolved slot error in Niagara N4 when graphics reference non-existent points.

Error when starting station exceeds licensed running station count (1) in Niagara AX.

Communication lost to Site Director or devices after changing engine hostname/IP

SNE engines show incorrect time or drift, especially M4-SNE models

Systematic checklist for diagnosing NTP time sync issues

SNE shows consistently high CPU usage and sluggish response

Implement proactive fault detection instead of waiting for complaints

Prevent temporary overrides from becoming permanent problems

Engine remains offline in Site Director tree after downloading new archive with SCT

Users cannot log in or station appears offline after applying security hardening

Operators cannot connect over HTTPS; Workbench shows SSL/TLS errors

How to proceed when assigned to fix a controller with no program loaded and no documentation

NAE/SNE devices get stuck at Connecting status after moving to new network infrastructure

Custom PX graphics no longer display on touchscreen devices after upgrading Niagara from 4.11 to 4.15+

BACnet MS/TP devices drop offline when all units power up simultaneously due to mixed cable gauges.

How to design and segment large BACnet MS/TP networks across multiple floors and buildings.

Metasys UI is slow to load, server is sluggish, CPU stays above 70%. Trends and graphics take 10+ seconds.

Metasys UI suddenly shows all readings as "????" across all graphics. Operators can't read setpoints or status.

Metasys 11 stops working after Windows update to Windows 11. Login fails or system becomes unresponsive.

Changing a setpoint in Metasys UI doesn't update the controller. Value reverts or doesn't register.

Niagara AX 3.8 license won't activate even with active SMA and correct Host ID. Common on upgrades or VM migrations.

JACE shows "Authentication Error" when connecting back to Supervisor. Scheduling and remote commands fail.

Points repeatedly go "orange" (fault) in Workbench view after override release or network interruptions.

Station suddenly stops responding, displays "Watchdog Timeout" in logs, and may reboot or freeze.

Workbench throws "Cannot Load Help Files" error when opening help or accessing webstation graphics.

Common issue where Niagara station fails to start after a Windows update due to Java path changes or service dependencies.