I'm on macOS Big Sur and trying to install Forge 1.16.5 36.1.0, I've also tried 36.1.4 but i can't open the installer. I keep getting the can't open error and so i tried from terminal. It starts working and I see SimpleInstaller next to the Apple symbol while this is printed: 

JVM info: Oracle Corporation - 1.8.0_281 - 25.281-b09

java.net.preferIPv4Stack=true

Found java version 1.8.0_281

 

but then i get this error and SimpleInstaller disappears:

Spoiler

Exception in thread "main"

java.lang.ExceptionInInitializerError

at javax.crypto.Cipher.getInstance(Cipher.java:518)

at sun.security.ssl.JsseJce.getCipher(JsseJce.java:189)

at sun.security.ssl.SSLCipher.isTransformationAvailable(SSLCipher.java:483)

at sun.security.ssl.SSLCipher.<init>(SSLCipher.java:472)

at sun.security.ssl.SSLCipher.<clinit>(SSLCipher.java:81)

at sun.security.ssl.CipherSuite.<clinit>(CipherSuite.java:67)

at sun.security.ssl.SSLContextImpl.getApplicableSupportedCipherSuites(SSLContextImpl.java:345)

at sun.security.ssl.SSLContextImpl.access$100(SSLContextImpl.java:46)

at sun.security.ssl.SSLContextImpl$AbstractTLSContext.<clinit>(SSLContextImpl.java:577)

at java.lang.Class.forName0(Native Method)

at java.lang.Class.forName(Class.java:264)

at java.security.Provider$Service.getImplClass(Provider.java:1728)

at java.security.Provider$Service.newInstance(Provider.java:1686)

at sun.security.jca.GetInstance.getInstance(GetInstance.java:236)

at sun.security.jca.GetInstance.getInstance(GetInstance.java:164)

at javax.net.ssl.SSLContext.getInstance(SSLContext.java:156)

at javax.net.ssl.SSLContext.getDefault(SSLContext.java:96)

at javax.net.ssl.SSLSocketFactory.getDefault(SSLSocketFactory.java:122)

at javax.net.ssl.HttpsURLConnection.getDefaultSSLSocketFactory(HttpsURLConnection.java:332)

at javax.net.ssl.HttpsURLConnection.<init>(HttpsURLConnection.java:289)

at sun.net.www.protocol.https.HttpsURLConnectionImpl.<init>(HttpsURLConnectionImpl.java:99)

at sun.net.www.protocol.https.Handler.openConnection(Handler.java:62)

at sun.net.www.protocol.https.Handler.openConnection(Handler.java:57)

at java.net.URL.openConnection(URL.java:1001)

at net.minecraftforge.installer.DownloadUtils.getConnection(DownloadUtils.java:197)

at net.minecraftforge.installer.DownloadUtils.downloadMirrors(DownloadUtils.java:253)

at net.minecraftforge.installer.json.Install.getMirror(Install.java:116)

at net.minecraftforge.installer.InstallerPanel.updateFilePath(InstallerPanel.java:370)

at net.minecraftforge.installer.InstallerPanel.<init>(InstallerPanel.java:351)

at net.minecraftforge.installer.SimpleInstaller.launchGui(SimpleInstaller.java:169)

at net.minecraftforge.installer.SimpleInstaller.main(SimpleInstaller.java:143)

Caused by: java.lang.SecurityException: Can not initialize cryptographic mechanism

at javax.crypto.JceSecurity.<clinit>(JceSecurity.java:93)

... 31 more

Caused by: java.lang.SecurityException: The jurisdiction policy files are not signed by the expected signer! (Policy files are specific per major JDK release.Ensure the correct version is installed.)

at javax.crypto.JarVerifier.verifyPolicySigned(JarVerifier.java:336)

at javax.crypto.JceSecurity.loadPolicies(JceSecurity.java:378)

at javax.crypto.JceSecurity.setupJurisdictionPolicies(JceSecurity.java:323)

at javax.crypto.JceSecurity.access$000(JceSecurity.java:50)

at javax.crypto.JceSecurity$1.run(JceSecurity.java:85)

at java.security.AccessController.doPrivileged(Native Method)

at javax.crypto.JceSecurity.<clinit>(JceSecurity.java:82)

... 31 more

I ran 1.16.5 before i tried to install and I searched google for hours. Please help!

Thanks a lot. It worked!

I am having the same issue. When you went to the linked site, which of the OpenJDK options did you choose? 8 (LTS), 11 (LTS, or 16 (Latest)?