Known Issue: FME Flow Engines Missing Failed to Connect to Job Queue

Issue

The Engines are missing from the FME Flow (formerly Server) Web UI. In the fmeserver.log there are errors similar to:

ERROR    RequestHandler-Thread   402902 : Failed to connect to Job Queue. Please ensure Job Queue is started.
ERROR    RequestHandler-Thread   Could not get a resource from the pool

In the fmeprocessmonitorengine.log there are messages similar to: 

INFORM   Thread-11   <HOSTNAME>_Engine1   Could not read from socket; connection may have been lost

Cause

The queue folder is missing from <FMEFlowSystemShare>\Resources\logs, or the account running the FME Flow Services does not have full control of this folder. Without this folder present or if the existing log file cannot be written to, the memurai.exe (FME Flow 2023+ win64) or redis-server.exe (all other FME Flow versions)  process will not start. This process is the FME Flow Queue and is essential for the FME Flow Engines to be able to connect. 

Workaround

1. Add a folder into <FMEFlowSystemShare>\Resources\logs called queue
2. If the queue folder already exists, delete the log file within this folder
3. Confirm the account running the FME Flow Services has full control of this folder (Properties > Security) 
4. Restart FME Flow