Mac not being able to verify the Developer
On a Mac you may get an error: “VASSAL cannot be opened because the developer cannot be verified. MacOS cannot verify that this app is free from malware.” What you can do to remedy the problem depends a little on the version of MacOS installed on your system.
Older version of MacOS
Click Okay on such a dialog.
Intermediate version of MacOS
If you have a more recent version of MacOS, Gatekeeper is probably active–MacOS will block VASSAL from running on the first attempt (because this isn’t what Apple considers a code-signed app).
Once you have tried to run Vassal once, you can follow the below to remedy the problem.
You’ll have to go into System Preferences → Security & Privacy to allow it to run. This only needs to be done once.*
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System Preferences → Security & Privacy
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Unlock (if needed) and click Open Anyway
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Click Open
Alternatively you can open a Finder window, type VASSAL into the search field, and double click on your new VASSAL install to open it for the first time - this will give you an “are you sure?” type dialog, and once you are past that then you will be able to open VASSAL normally in the future.
Relatively new versions of MacOS
When you launch Vassal the first time after installation, you may see the pop-up dialog
To get Vassal to run, follow the below procedure (these steps need only be done once)
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Click the ? button in the top-right of the dialog.
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This will take you to a help page
Click the link Open Privacy and Security settings for me
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That will open up the Settings app for you in the Privacy and Security sub-page
Scroll down to the heading Security and find
“VASSAL” was blocked to protect your Mac
Press the Open Anyway button
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A new dialog will appear
Press the Open Anyway button. -
You may be presented with yet another dialog asking you to authorise as system administrator using either a biometric (e.g., finger print) or password.
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You may also need to give Vassal permissions to access your folders.
Alternative solution 1
- Download MacOS disk image (
.dmg) from the Vassal the download page. - Install as per usual - see here
- Open a Terminal via Finder→Applications→Utilities→Terminal
- Type in the command
and press$ xattr -d com.apple.quarantine /Applications/VASSAL.appEnter.
Voila, you should have removed the quarantine attribute from Vassal, and you should be able to execute the application as per usual.
Alternative solution 2
Use the web-client curl which is part of MacOS. Follow the steps below:
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Go to the GitHub Release page
- Find the version of VASSAL you are interested in. For example
VASSAL-3.7.20-macos-universal.dmg. - Right click the link and select Copy link address (or similar).
- Find the version of VASSAL you are interested in. For example
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Open a terminal via Finder→Applications→Utilities→Terminal
(If you have not used a terminal before, perhaps this solution is not for you. The terminal is a very powerful tool to interact with the operating system in ways you’ve never imagined.)- In the terminal, change directory to your
Downloadsdirectory$ cd Downloads` - In the terminal, type
where$ curl -LO <paste copied link>`<paste copied link>is the link you copied above pasted into the terminal (⌘-V), and then press enter. - The file will start downloading showing you a nice progress bar
- In the terminal, change directory to your
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Once downloaded, double-click the VASSAL
.dmgnow in yourDownloadsfolder, and install per usual instructions - see here.
Explanation
MacOS attaches a quarantine attribute to files downloaded by web browsers, which prompts intervention by the Gatekeeper feature. Downloads performed by command line tools like curl and wget do not have this attribute set.
“this file isn’t commonly downloaded” warning
On Windows, when downloading a newly-released version of VASSAL with Edge, Chrome, and other browsers, Microsoft SmartScreen may intervene with a warning that the file isn’t commonly downloaded. Respond to these prompts by choosing to keep the file anyway.
Edge warns about the installer download–start by choosing “Keep”.
On the repeated warning, choose Keep anyway to save the download
In Chrome, choose Keep to save the download from the warning dialog
“Windows protected your PC” when running the installer
Windows Defender sometimes blocks VASSAL’s installer from running: “Microsoft Defender SmartScreen prevented an unrecognized app from starting. Running this app might put your PC at risk.”
Windows checks whether executables downloaded from the internet are signed and how often they’ve been downloaded (globally). Our installer is not presently signed, so you may see this message if you try installing VASSAL shortly after a new release. It does not indicate a problem with the installer.
Click More info in the dialog to reveal the Run anyway button to run the installer.
Antivirus scanner quarantines the installer
Some antivirus scanners (AVG and Avast in particular) mistdetect Vassal’s Windows installers as a threat. The way to fix this problem, both for yourself and for others, is to report the false positives to your AV vendor. (E.g., there is a “Report as false positive” link in the screenshot from AVG shown here.)
If you want to verify that your installer is the installer we released, you can check the SHA256 hash of your installer file against the list we publish. (If you need a tool for computing the SHA256 hash of the installer file you have, a simple solution is to try uploading the file to VirusTotal, which will compute the file’s SHA256 hash and display it.)
