UT does not start

A general experience in advance: the coincidence of events does not necessarily mean a causal conclusion. Nevertheless, it usually helps to remember what was changed last.

There are a few general things you can check and partly already do:

• Does ArcMap not start even without UT?
  Procedure: So don't use UT, don't use a startup script, just start ArcMap with an empty map (if ArcMap gets so far).
  Do Esri license warnings appear?
  
  
• Does only UT not start or can the UT extension not be activated?
  Do UT license warnings appear?
  If you are using a startup script, are the settings, paths, etc. correct?
  There is a separate article about the UT extension.
  
  
• Can another user log on to the computer and run the workflow successfully without a crash?
  Possibly only the Normal.mxt is damaged?
  Then it often helps to delete the
  C:\Users\<User>\AppData\Roaming\ESRI\Desktop10.6\ArcMap\Templates\Normal.mxt.
  If that doesn't help, reset your application profile.
  Rename your UT profile (%AppData%\AED-SICAD\ArcFM_UT) (for example, to ...\ArcFM_UT_sic).
  If that doesn't help, rename your Esri profile (%AppData%\AED-SICAD\ArcMap) (e.g. to ArcMap_sic).
  
  
• If an MXD or dataset crashes, the MXD or data may be corrupted.
  Copy your layers, start a new empty MXD, and paste it into the new data frame.
  If it is a complex MXD that would take a lot of time to recreate from scratch, try repairing the MXD with MXD Doctor.
  Back up your data and try to recreate the data that is causing the crash.
  
  
• Is there a problem with system resources?
  Maybe a Windows update left a backup (it should) and it took up too much space? Or a drive is full for some other reason? Or %TEMP%, or other variables points to a non-existing folder? Etc.
  
  
• Make sure your graphics card drivers are up to date and correctly configured.
  This is a likely solution if ArcMap fails at startup, while ArcCatalog can be started without problems. (Problems like this can caused by a graphics driver update and also by a Windows update).
  Maybe there are settings in the graphics driver that fix the problem, e.g. NVIDIA -> Manage 3D Settings -> Make Custom Adjustments for ArcMap.exe.
  
  
• Start ArcMap with the log file option. Maybe the output will give you a hint.
  
  
• Go to Programs and Features - right click on ArcGIS Desktop (if ArcMap does not start even without UT) or on UT (if ArcMap starts without UT) - Repair.
  Please note that after repairing ArcGIS UT has to be repaired as well. Also after UT, any UT Addon packages may need to be repaired or uninstalled and reinstalled (whether this is necessary, read the instructions or ask your customer support).
  
  
• A complete uninstall and reinstall of UT and potentially ArcGIS should be the last option, unless it is time to update anyway.