Checking if installation is fresh or upgrade does

Question

I try to run same installer for fresh installation and upgrade.

In case it is an upgrade: some files and folders shouldn’t be copy and server.bat shouldn’t be run. I use the function as it has been answered on the question (Can Inno Setup respond differently to a new install and an update?) and I used same AppId and defined the #SetupReg as it shown, and install the app for first time, and everything is good, but when I searched Setup Log I found that:

Line 122: 2019-02-27 15:46:13.797   Creating new uninstall key: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall\{FDDFBC15-7B5C-4580-AD69-F54B8087A52E}_is1

Then I searched Registry and above path doesn’t exist, but I found the actually SetupReg path in

HKLM\Softwares\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall\ {FDDFBC15-7B5C-4580-AD69-F54B8087A52E}_is1

I already defined it as script blow, the path in script was:

HKLM\ Software\Microsoft\Windows\CurrentVersion\Uninstall\" + AppId + "_is1

I edit MyApp.iss and changed values of MyAppVersion to "1.1.0" and VersionInfoVersion to 1.1.0, and run installer again, I expected it will run an upgrade (files and folder which has check: not IsUpgrade shouldn’t copy or run) and it will disable installation directory page. But nothing expected happen. The function IsUpgrade didn’t work successfully, files and folders which has check: not IsUpgrade have been copied normally and overwrote the old one, even the server.bat overwrote the old one and also run after installation finished. What’s going wrong? Is it because of #SetupReg or function IsUpgrade or iss script?

#define MyAppName "Medfor"
#define MyAppVersion "1.0.0"
#define MyAppExeName "Medfor.exe"
#define AppId "{{FDDFBC15-7B5C-4580-AD69-F54B8087A52E}"
#define SetupReg "Software\Microsoft\Windows\CurrentVersion\Uninstall\" + AppId + "_is1"
#define SetupAppPathReg "Inno Setup: App Path"

[Setup]
AppId={#AppId}
AppName={#MyAppName}
AppVersion={#MyAppVersion}

[Files]
Source: "build\server.bat"; DestDir: "{app}"; Flags: ignoreversion; Check: not IsUpgrade

[Run]
Filename: "{app}\server.bat"; \
    Flags: postinstall skipifsilent runascurrentuser waituntilterminated; \
    Description: "{cm:LaunchProgram,{#StringChange(MyAppName, '&', '&&')}}"; \
    Check: not IsUpgrade

[Code]
function IsUpgrade: Boolean;
var
  S: string;
begin
  Result :=
    RegQueryStringValue(HKLM, '{#SetupReg}', '{#SetupAppPathReg}', S) or
    RegQueryStringValue(HKCU, '{#SetupReg}', '{#SetupAppPathReg}', S);
end;

First Installation Log:

2019-02-27 15:45:48.996   Log opened. (Time zone: UTC+03:00)
2019-02-27 15:45:48.996   Setup version: Inno Setup version 5.6.1 (a)
2019-02-27 15:45:48.996   Original Setup EXE: C:\Users\user\Documents\Output\Medfor-setup.exe
2019-02-27 15:45:48.996   Setup command line: /SL5="$2307BA,9890028,58368,C:\Users\user\Documents\Output\Medfor-setup.exe" /SPAWNWND=$2B04B6 /NOTIFYWND=$390B4C 
2019-02-27 15:45:48.997   Windows version: 6.3.9600  (NT platform: Yes)
2019-02-27 15:45:48.997   64-bit Windows: Yes
2019-02-27 15:45:48.997   Processor architecture: x64
2019-02-27 15:45:48.997   User privileges: Administrative
2019-02-27 15:45:48.999   64-bit install mode: No
2019-02-27 15:45:49.004   Created temporary directory: C:\Users\user\AppData\Local\Temp\is-IH9A3.tmp
2019-02-27 15:46:11.561   Starting the installation process.
2019-02-27 15:46:11.690   Creating directory: C:\Program Files (x86)\Medfor
2019-02-27 15:46:11.690   Creating directory: C:\Program Files (x86)\Medfor\App
2019-02-27 15:46:11.691   Creating directory: C:\Program Files (x86)\Medfor\App\sections
2019-02-27 15:46:11.691   Creating directory: C:\Program Files (x86)\Medfor\App\sections\templates_sections
2019-02-27 15:46:11.691   Creating directory: C:\Program Files (x86)\Medfor\App\sections\templates_sections\headers
2019-02-27 15:46:11.692   Creating directory: C:\Program Files (x86)\Medfor\App\sections\templates_sections\modals
2019-02-27 15:46:11.693   Creating directory: C:\Program Files (x86)\Medfor\App\templates
2019-02-27 15:46:11.693   Creating directory: C:\Program Files (x86)\Medfor\App\templates\errors
2019-02-27 15:46:11.694   Creating directory: C:\Program Files (x86)\Medfor\App\templates\menus
2019-02-27 15:46:11.694   Creating directory: C:\Program Files (x86)\Medfor\App\templates\modals
2019-02-27 15:46:11.695   Creating directory: C:\Program Files (x86)\Medfor\Uploads
2019-02-27 15:46:11.696   Directory for uninstall files: C:\Program Files (x86)\Medfor
2019-02-27 15:46:11.696   Creating new uninstall log: C:\Program Files (x86)\Medfor\unins000.dat
2019-02-27 15:46:11.701   -- File entry --
2019-02-27 15:46:11.702   Dest filename: C:\Program Files (x86)\Medfor\unins000.exe
2019-02-27 15:46:11.705   Time stamp of our file: 2019-02-27 15:45:48.834
2019-02-27 15:46:11.705   Installing the file.
2019-02-27 15:46:11.719   Uninstaller requires administrator: Yes
2019-02-27 15:46:11.720   Successfully installed the file.
2019-02-27 15:46:11.721   -- File entry --
2019-02-27 15:46:11.722   Dest filename: C:\Program Files (x86)\Medfor\mfcm90u.dll
2019-02-27 15:46:11.722   Time stamp of our file: 2018-11-25 14:38:14.000
2019-02-27 15:46:11.723   Installing the file.
2019-02-27 15:46:11.731   Successfully installed the file.
2019-02-27 15:46:11.731   -- File entry --
2019-02-27 15:46:11.732   Dest filename: C:\Program Files (x86)\Medfor\Microsoft.VC90.CRT.manifest
2019-02-27 15:46:11.733   Time stamp of our file: 2018-11-25 14:38:08.000
2019-02-27 15:46:11.733   Installing the file.
2019-02-27 15:46:11.735   Successfully installed the file.
2019-02-27 15:46:11.736   -- File entry --
2019-02-27 15:46:11.737   Dest filename: C:\Program Files (x86)\Medfor\Microsoft.VC90.MFC.manifest
2019-02-27 15:46:11.738   Time stamp of our file: 2018-11-25 14:38:14.000
2019-02-27 15:46:11.738   Installing the file.
2019-02-27 15:46:11.741   Successfully installed the file.
2019-02-27 15:46:11.741   -- File entry --
2019-02-27 15:46:11.743   Dest filename: C:\Program Files (x86)\Medfor\msvcm90.dll
2019-02-27 15:46:11.743   Time stamp of our file: 2018-11-25 14:38:08.000
2019-02-27 15:46:11.743   Installing the file.
2019-02-27 15:46:11.766   Successfully installed the file.
2019-02-27 15:46:11.766   -- File entry --
2019-02-27 15:46:11.767   Dest filename: C:\Program Files (x86)\Medfor\msvcp90.dll
2019-02-27 15:46:11.768   Time stamp of our file: 2018-11-25 14:38:08.000
2019-02-27 15:46:11.768   Installing the file.
2019-02-27 15:46:11.837   Successfully installed the file.
2019-02-27 15:46:11.837   -- File entry --
2019-02-27 15:46:11.839   Dest filename: C:\Program Files (x86)\Medfor\msvcr90.dll
2019-02-27 15:46:11.839   Time stamp of our file: 2018-11-25 14:38:08.000
2019-02-27 15:46:11.839   Installing the file.
2019-02-27 15:46:11.913   Successfully installed the file.
2019-02-27 15:46:11.914   -- File entry --
2019-02-27 15:46:11.914   Dest filename: C:\Program Files (x86)\Medfor\service.bat
2019-02-27 15:46:11.915   Time stamp of our file: 2018-12-16 16:53:52.000
2019-02-27 15:46:11.915   Installing the file.
2019-02-27 15:46:11.917   Successfully installed the file.
2019-02-27 15:46:11.917   -- File entry --
2019-02-27 15:46:11.918   Dest filename: C:\Program Files (x86)\Medfor\sqlite3.dll
2019-02-27 15:46:11.918   Time stamp of our file: 2018-11-25 14:38:26.000
2019-02-27 15:46:11.918   Installing the file.
2019-02-27 15:46:12.012   Successfully installed the file.
2019-02-27 15:46:12.012   -- File entry --
2019-02-27 15:46:12.013   Dest filename: C:\Program Files (x86)\Medfor\tcl85.dll
2019-02-27 15:46:12.013   Time stamp of our file: 2018-11-25 14:38:26.000
2019-02-27 15:46:12.013   Installing the file.
2019-02-27 15:46:12.143   Successfully installed the file.
2019-02-27 15:46:12.143   -- File entry --
2019-02-27 15:46:12.145   Dest filename: C:\Program Files (x86)\Medfor\medfor.dll
2019-02-27 15:46:12.145   Time stamp of our file: 2019-02-27 13:15:42.000
2019-02-27 15:46:12.145   Installing the file.
2019-02-27 15:46:12.148   Successfully installed the file.
2019-02-27 15:46:12.149   -- File entry --
2019-02-27 15:46:12.149   Dest filename: C:\Program Files (x86)\Medfor\Medfor.exe
2019-02-27 15:46:12.150   Time stamp of our file: 2018-10-29 02:05:20.000
2019-02-27 15:46:12.150   Installing the file.
2019-02-27 15:46:12.790   Successfully installed the file.
2019-02-27 15:46:12.791   -- File entry --
2019-02-27 15:46:12.791   Dest filename: C:\Program Files (x86)\Medfor\mfc90.dll
2019-02-27 15:46:12.792   Time stamp of our file: 2018-11-25 14:38:14.000
2019-02-27 15:46:12.792   Installing the file.
2019-02-27 15:46:13.287   Successfully installed the file.
2019-02-27 15:46:13.287   -- File entry --
2019-02-27 15:46:13.288   Dest filename: C:\Program Files (x86)\Medfor\mfc90u.dll
2019-02-27 15:46:13.288   Time stamp of our file: 2018-11-25 14:38:14.000
2019-02-27 15:46:13.288   Installing the file.
2019-02-27 15:46:13.541   Successfully installed the file.
2019-02-27 15:46:13.541   -- File entry --
2019-02-27 15:46:13.542   Dest filename: C:\Program Files (x86)\Medfor\mfcm90.dll
2019-02-27 15:46:13.542   Time stamp of our file: 2018-11-25 14:38:14.000
2019-02-27 15:46:13.542   Installing the file.
2019-02-27 15:46:13.549   Successfully installed the file.
2019-02-27 15:46:13.549   -- File entry --
2019-02-27 15:46:13.550   Dest filename: C:\Program Files (x86)\Medfor\App\templates\errors\403.html
2019-02-27 15:46:13.550   Time stamp of our file: 2018-11-21 16:21:04.000
2019-02-27 15:46:13.550   Installing the file.
2019-02-27 15:46:13.552   Successfully installed the file.
2019-02-27 15:46:13.552   -- File entry --
2019-02-27 15:46:13.553   Dest filename: C:\Program Files (x86)\Medfor\App\templates\errors\404.html
2019-02-27 15:46:13.553   Time stamp of our file: 2018-11-21 16:21:04.000
2019-02-27 15:46:13.553   Installing the file.
2019-02-27 15:46:13.555   Successfully installed the file.
2019-02-27 15:46:13.555   -- File entry --
2019-02-27 15:46:13.556   Dest filename: C:\Program Files (x86)\Medfor\Uploads\Capture.gif
2019-02-27 15:46:13.557   Time stamp of our file: 2018-07-31 21:51:14.000
2019-02-27 15:46:13.557   Installing the file.
2019-02-27 15:46:13.565   Successfully installed the file.
2019-02-27 15:46:13.566   -- Icon entry --
2019-02-27 15:46:13.566   Dest filename: C:\ProgramData\Microsoft\Windows\Start Menu\Programs\Medfor.lnk
2019-02-27 15:46:13.568   Creating the icon.
2019-02-27 15:46:13.794   Successfully created the icon.
2019-02-27 15:46:13.797   Saving uninstall information.
2019-02-27 15:46:13.797   Deleting any uninstall keys left over from previous installs
2019-02-27 15:46:13.797   Creating new uninstall key: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall\{FDDFBC15-7B5C-4580-AD69-F54B8087A52E}_is1
2019-02-27 15:46:13.797   Writing uninstall key values.
2019-02-27 15:46:13.961   Installation process succeeded.
2019-02-27 15:46:13.963   Need to restart Windows? No
2019-02-27 15:46:21.260   -- Run entry --
2019-02-27 15:46:21.260   Run as: Current user
2019-02-27 15:46:21.260   Type: Exec
2019-02-27 15:46:21.260   Filename: C:\Program Files (x86)\Medfor\service.bat
2019-02-27 15:46:27.225   Process exit code: 1
2019-02-27 15:46:27.225   -- Run entry --
2019-02-27 15:46:27.225   Run as: Original user
2019-02-27 15:46:27.225   Type: Exec
2019-02-27 15:46:27.225   Filename: C:\Program Files (x86)\Medfor\Medfor.exe

Second Installation Log (Expected Upgrade)

2019-02-27 16:42:48.069   Log opened. (Time zone: UTC+03:00)
2019-02-27 16:42:48.070   Setup version: Inno Setup version 5.6.1 (a)
2019-02-27 16:42:48.070   Original Setup EXE: C:\Users\user\Documents\Output\Medfor-1.1.0-setup.exe
2019-02-27 16:42:48.070   Setup command line: /SL5="$4A052C,9889159,58368,C:\Users\user\Documents\Output\Medfor-1.1.0-setup.exe" /SPAWNWND=$9C0140 /NOTIFYWND=$5F02BC 
2019-02-27 16:42:48.070   Windows version: 6.3.9600  (NT platform: Yes)
2019-02-27 16:42:48.070   64-bit Windows: Yes
2019-02-27 16:42:48.071   Processor architecture: x64
2019-02-27 16:42:48.071   User privileges: Administrative
2019-02-27 16:42:48.074   64-bit install mode: No
2019-02-27 16:42:48.082   Created temporary directory: C:\Users\user\AppData\Local\Temp\is-Q7EVG.tmp
2019-02-27 16:43:13.652   Starting the installation process.
2019-02-27 16:43:13.662   Directory for uninstall files: C:\Program Files (x86)\Medfor
2019-02-27 16:43:13.662   Will append to existing uninstall log: C:\Program Files (x86)\Medfor\unins000.dat
2019-02-27 16:43:13.668   -- File entry --
2019-02-27 16:43:13.669   Dest filename: C:\Program Files (x86)\Medfor\unins000.exe
2019-02-27 16:43:13.673   Time stamp of our file: 2019-02-27 16:42:47.947
2019-02-27 16:43:13.673   Dest file exists.
2019-02-27 16:43:13.673   Time stamp of existing file: 2019-02-27 15:45:48.834
2019-02-27 16:43:13.673   Version of our file: 51.52.0.0
2019-02-27 16:43:13.674   Version of existing file: 51.52.0.0
2019-02-27 16:43:13.674   Installing the file.
2019-02-27 16:43:13.700   Uninstaller requires administrator: Yes
2019-02-27 16:43:13.700   Leaving temporary file in place for now.
2019-02-27 16:43:13.701   -- File entry --
2019-02-27 16:43:13.703   Dest filename: C:\Program Files (x86)\Medfor\mfcm90u.dll
2019-02-27 16:43:13.703   Time stamp of our file: 2018-11-25 14:38:14.000
2019-02-27 16:43:13.703   Dest file exists.
2019-02-27 16:43:13.703   Time stamp of existing file: 2018-11-25 14:38:14.000
2019-02-27 16:43:13.704   Installing the file.
2019-02-27 16:43:13.716   Successfully installed the file.
2019-02-27 16:43:13.716   -- File entry --
2019-02-27 16:43:13.718   Dest filename: C:\Program Files (x86)\Medfor\Microsoft.VC90.CRT.manifest
2019-02-27 16:43:13.719   Time stamp of our file: 2018-11-25 14:38:08.000
2019-02-27 16:43:13.719   Dest file exists.
2019-02-27 16:43:13.719   Time stamp of existing file: 2018-11-25 14:38:08.000
2019-02-27 16:43:13.719   Installing the file.
2019-02-27 16:43:13.724   Successfully installed the file.
2019-02-27 16:43:13.725   -- File entry --
2019-02-27 16:43:13.727   Dest filename: C:\Program Files (x86)\Medfor\Microsoft.VC90.MFC.manifest
2019-02-27 16:43:13.728   Time stamp of our file: 2018-11-25 14:38:14.000
2019-02-27 16:43:13.728   Dest file exists.
2019-02-27 16:43:13.728   Time stamp of existing file: 2018-11-25 14:38:14.000
2019-02-27 16:43:13.728   Installing the file.
2019-02-27 16:43:13.733   Successfully installed the file.
2019-02-27 16:43:13.734   -- File entry --
2019-02-27 16:43:13.735   Dest filename: C:\Program Files (x86)\Medfor\msvcm90.dll
2019-02-27 16:43:13.736   Time stamp of our file: 2018-11-25 14:38:08.000
2019-02-27 16:43:13.736   Dest file exists.
2019-02-27 16:43:13.736   Time stamp of existing file: 2018-11-25 14:38:08.000
2019-02-27 16:43:13.736   Installing the file.
2019-02-27 16:43:13.770   Successfully installed the file.
2019-02-27 16:43:13.771   -- File entry --
2019-02-27 16:43:13.773   Dest filename: C:\Program Files (x86)\Medfor\msvcp90.dll
2019-02-27 16:43:13.773   Time stamp of our file: 2018-11-25 14:38:08.000
2019-02-27 16:43:13.774   Dest file exists.
2019-02-27 16:43:13.774   Time stamp of existing file: 2018-11-25 14:38:08.000
2019-02-27 16:43:13.774   Installing the file.
2019-02-27 16:43:13.870   Successfully installed the file.
2019-02-27 16:43:13.871   -- File entry --
2019-02-27 16:43:13.872   Dest filename: C:\Program Files (x86)\Medfor\msvcr90.dll
2019-02-27 16:43:13.873   Time stamp of our file: 2018-11-25 14:38:08.000
2019-02-27 16:43:13.873   Dest file exists.
2019-02-27 16:43:13.873   Time stamp of existing file: 2018-11-25 14:38:08.000
2019-02-27 16:43:13.873   Installing the file.
2019-02-27 16:43:13.977   Successfully installed the file.
2019-02-27 16:43:13.978   -- File entry --
2019-02-27 16:43:13.980   Dest filename: C:\Program Files (x86)\Medfor\server.bat
2019-02-27 16:43:13.981   Time stamp of our file: 2019-02-27 16:37:22.000
2019-02-27 16:43:13.981   Dest file exists.
2019-02-27 16:43:13.981   Time stamp of existing file: 2019-02-27 16:40:59.984
2019-02-27 16:43:13.981   Installing the file.
2019-02-27 16:43:13.985   Successfully installed the file.
2019-02-27 16:43:13.986   -- File entry --
2019-02-27 16:43:13.987   Dest filename: C:\Program Files (x86)\Medfor\sqlite3.dll
2019-02-27 16:43:13.988   Time stamp of our file: 2018-11-25 14:38:26.000
2019-02-27 16:43:13.988   Dest file exists.
2019-02-27 16:43:13.988   Time stamp of existing file: 2018-11-25 14:38:26.000
2019-02-27 16:43:13.988   Installing the file.
2019-02-27 16:43:14.159   Successfully installed the file.
2019-02-27 16:43:14.193   -- File entry --
2019-02-27 16:43:14.194   Dest filename: C:\Program Files (x86)\Medfor\tcl85.dll
2019-02-27 16:43:14.195   Time stamp of our file: 2018-11-25 14:38:26.000
2019-02-27 16:43:14.195   Dest file exists.
2019-02-27 16:43:14.195   Time stamp of existing file: 2018-11-25 14:38:26.000
2019-02-27 16:43:14.195   Installing the file.
2019-02-27 16:43:14.421   Successfully installed the file.
2019-02-27 16:43:14.422   -- File entry --
2019-02-27 16:43:14.424   Dest filename: C:\Program Files (x86)\Medfor\medfor.dll
2019-02-27 16:43:14.424   Time stamp of our file: 2019-02-27 13:15:42.000
2019-02-27 16:43:14.425   Dest file exists.
2019-02-27 16:43:14.425   Time stamp of existing file: 2019-02-27 13:15:42.000
2019-02-27 16:43:14.425   Installing the file.
2019-02-27 16:43:14.431   Successfully installed the file.
2019-02-27 16:43:14.431   -- File entry --
2019-02-27 16:43:14.433   Dest filename: C:\Program Files (x86)\Medfor\Medfor.exe
2019-02-27 16:43:14.434   Time stamp of our file: 2018-10-29 02:05:20.000
2019-02-27 16:43:14.434   Dest file exists.
2019-02-27 16:43:14.434   Time stamp of existing file: 2018-10-29 02:05:20.000
2019-02-27 16:43:14.434   Installing the file.
2019-02-27 16:43:15.386   Successfully installed the file.
2019-02-27 16:43:15.387   -- File entry --
2019-02-27 16:43:15.388   Dest filename: C:\Program Files (x86)\Medfor\mfc90.dll
2019-02-27 16:43:15.389   Time stamp of our file: 2018-11-25 14:38:14.000
2019-02-27 16:43:15.389   Dest file exists.
2019-02-27 16:43:15.389   Time stamp of existing file: 2018-11-25 14:38:14.000
2019-02-27 16:43:15.389   Installing the file.
2019-02-27 16:43:16.087   Successfully installed the file.
2019-02-27 16:43:16.088   -- File entry --
2019-02-27 16:43:16.089   Dest filename: C:\Program Files (x86)\Medfor\mfc90u.dll
2019-02-27 16:43:16.089   Time stamp of our file: 2018-11-25 14:38:14.000
2019-02-27 16:43:16.089   Dest file exists.
2019-02-27 16:43:16.089   Time stamp of existing file: 2018-11-25 14:38:14.000
2019-02-27 16:43:16.090   Installing the file.
2019-02-27 16:43:16.432   Successfully installed the file.
2019-02-27 16:43:16.432   -- File entry --
2019-02-27 16:43:16.434   Dest filename: C:\Program Files (x86)\Medfor\mfcm90.dll
2019-02-27 16:43:16.435   Time stamp of our file: 2018-11-25 14:38:14.000
2019-02-27 16:43:16.435   Dest file exists.
2019-02-27 16:43:16.435   Time stamp of existing file: 2018-11-25 14:38:14.000
2019-02-27 16:43:16.435   Installing the file.
2019-02-27 16:43:16.450   Successfully installed the file.
2019-02-27 16:43:16.450   -- File entry --
2019-02-27 16:43:16.451   Dest filename: C:\Program Files (x86)\Medfor\App\templates\errors\403.html
2019-02-27 16:43:16.452   Time stamp of our file: 2018-11-21 16:21:04.000
2019-02-27 16:43:16.452   Dest file exists.
2019-02-27 16:43:16.452   Time stamp of existing file: 2018-11-21 16:21:04.000
2019-02-27 16:43:16.452   Installing the file.
2019-02-27 16:43:16.455   Successfully installed the file.
2019-02-27 16:43:16.456   -- File entry --
2019-02-27 16:43:16.457   Dest filename: C:\Program Files (x86)\Medfor\App\templates\errors\404.html
2019-02-27 16:43:16.457   Time stamp of our file: 2018-11-21 16:21:04.000
2019-02-27 16:43:16.457   Dest file exists.
2019-02-27 16:43:16.457   Time stamp of existing file: 2018-11-21 16:21:04.000
2019-02-27 16:43:16.457   Installing the file.
2019-02-27 16:43:16.460   Successfully installed the file.
2019-02-27 16:43:16.460   -- File entry --
2019-02-27 16:43:16.461   Dest filename: C:\Program Files (x86)\Medfor\Uploads\Capture.gif
2019-02-27 16:43:16.462   Time stamp of our file: 2018-07-31 21:51:14.000
2019-02-27 16:43:16.462   Dest file exists.
2019-02-27 16:43:16.462   Time stamp of existing file: 2018-07-31 21:51:14.000
2019-02-27 16:43:16.462   Installing the file.
2019-02-27 16:43:16.478   Successfully installed the file.
2019-02-27 16:43:16.480   -- Icon entry --
2019-02-27 16:43:16.480   Dest filename: C:\ProgramData\Microsoft\Windows\Start Menu\Programs\Medfor.lnk
2019-02-27 16:43:16.483   Creating the icon.
2019-02-27 16:43:16.630   Successfully created the icon.
2019-02-27 16:43:16.634   Saving uninstall information.
2019-02-27 16:43:16.634   Renaming uninstaller.
2019-02-27 16:43:16.635   Deleting any uninstall keys left over from previous installs
2019-02-27 16:43:16.636   Creating new uninstall key: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall\{FDDFBC15-7B5C-4580-AD69-F54B8087A52E}_is1
2019-02-27 16:43:16.637   Writing uninstall key values.
2019-02-27 16:43:16.828   Installation process succeeded.
2019-02-27 16:43:16.830   Need to restart Windows? No
2019-02-27 16:43:21.677   -- Run entry --
2019-02-27 16:43:21.677   Run as: Current user
2019-02-27 16:43:21.677   Type: Exec
2019-02-27 16:43:21.677   Filename: C:\Program Files (x86)\Medfor\server.bat
2019-02-27 16:43:22.055   Process exit code: 0
2019-02-27 16:43:22.055   -- Run entry --
2019-02-27 16:43:22.055   Run as: Original user
2019-02-27 16:43:22.055   Type: Exec
2019-02-27 16:43:22.055   Filename: C:\Program Files (x86)\Medfor\Medfor.exe

Answer 1

That's because your "AddId" is {xxx}, not {{xxx} (check the registry key path in your question). The double curly bracket is needed in AppId directive, as in Inno Setup directives a curly bracket have a special meaning (for constants). If you want to use a curly bracket literally, you have to double it.

But in Pascal Script code, a curly bracket has no special meaning. So if you use two, your Pascal Script code will explicitly look for {{xxx} in the registry. And naturally, it won't find it there, as there's {xxx}.

One way to solve this (without duplicating xxx between the directive and the code) is by doubling the curly bracket using preprocessor in the AppId directive only:

#define AppId "{FDDFBC15-7B5C-4580-AD69-F54B8087A52E}"
; One curly bracket for Pascal Script code
#define SetupReg "Software\Microsoft\Windows\CurrentVersion\Uninstall\" + AppId + "_is1"

[Setup]
; Two curly brackets for directive
AppId={#StringChange(AppId, '{', '{{')}