I have a single user failing on a product upgrade during ExecuteAction:
MSI (c) (D4:4C) [13:04:42:038]: Doing action: ExecuteAction
Action start 13:04:42: ExecuteAction.
MSI (c) (D4:4C) [13:04:42:044]: PROPERTY CHANGE: Adding SECONDSEQUENCE property. Its value is '1'.
MSI (c) (D4:4C) [13:04:42:044]: Grabbed execution mutex.
MSI (c) (D4:4C) [13:04:42:044]: Incrementing counter to disable shutdown. Counter after increment: 0
MSI (c) (D4:4C) [13:04:42:046]: Switching to server: MY_SETUP_TYPE="Advanced" AI_INSTALL="1" APPDIR="C:\Users\MyUser\AppData\Local\Programs\MyApplication" TARGETDIR="C:\" SHORTCUTDIR="C:\Users\MyUser\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\MyApplication" LOG_FILE_PATH="C:\Users\MyUser\AppData\Local\Temp" AI_SH_DIR="MyApplication" AI_STARTMENU_SH="1" START_MINIMIZED="1" AI_DOTNET40_SEARCH="#1" AI_DOTNET451_SEARCH="#394254" AI_DOTNET452_SEARCH="#394254" AI_DOTNET45_SEARCH="4.6.01038" CURRENTDIRECTORY="C:\Users\MyUser\Downloads" CLIENTUILEVEL="0" CLIENTPROCESSID="8660" ACTION="INSTALL" USERNAME="Windows User" SOURCEDIR="C:\Users\MyUser\Downloads\" EXECUTEACTION="INSTALL" IS_PRODUCTION_MODE="1" AI_SYSTEM_DPI="96" AI_SYSTEM_DPI_SCALE="100" SECONDSEQUENCE="1" ROOTDRIVE="C:\" SHORTCUT_ARGS="null" IS_OUTLOOK_RUNNING="0" AI_SH_INITED="1" PERFORMOPERATION_RESULT="1" MSIINSTALLPERUSER="1" ADDLOCAL=Feature_1,MainFeature,Feature_2,TextExtraction,MyOutlookCommon,FileConnector,RapidConnector,Stellent,MyOutlook32,MyWebBrowser,Filters,SEVConnector,IMAPConnector,SharepointConnector,MyOutlook64
MSI (s) (94:E8) [13:04:42:060]: Running installation inside multi-package transaction C:\Users\MyUser\Downloads\MyApplication.msi
MSI (s) (94:E8) [13:04:42:060]: Grabbed execution mutex.
MSI (s) (94:10) [13:04:42:065]: MainEngineThread is returning 1603
MSI (s) (94:E8) [13:04:42:070]: User policy value 'DisableRollback' is 0
MSI (s) (94:E8) [13:04:42:070]: Machine policy value 'DisableRollback' is 0
MSI (s) (94:E8) [13:04:42:070]: Incrementing counter to disable shutdown. Counter after increment: 0
MSI (s) (94:E8) [13:04:42:072]: Note: 1: 1402 2: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Installer\Rollback\Scripts 3: 2
MSI (s) (94:E8) [13:04:42:075]: Note: 1: 1402 2: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Installer\Rollback\Scripts 3: 2
MSI (s) (94:E8) [13:04:42:076]: Decrementing counter to disable shutdown. If counter >= 0, shutdown will be denied. Counter after decrement: -1
MSI (c) (D4:4C) [13:04:42:080]: Back from server. Return value: 1603
MSI (c) (D4:4C) [13:04:42:080]: Decrementing counter to disable shutdown. If counter >= 0, shutdown will be denied. Counter after decrement: -1
MSI (c) (D4:4C) [13:04:42:080]: PROPERTY CHANGE: Deleting SECONDSEQUENCE property. Its current value is '1'.
Action ended 13:04:42: ExecuteAction. Return value 3.
I've not encountered this before and so I'm not sure what might cause the MainEngineThread to fail during ExecuteAction.