Java SecurityException — What It Means & How to Fix It

What Does This Error Mean?

SecurityException means Java's security system blocked something your code tried to do. This commonly happens in sandboxed environments like applets, app servers, or strict policy configurations. It can also appear on Android when your app lacks a required permission.

Affected Models

Java 8
Java 11
Java 17
Java 21
Android (Java/Kotlin)

Common Causes

Reading or writing a file that the SecurityManager disallows
Starting a new thread in a restricted environment
Attempting network access without the required permission
Missing Android manifest permission (e.g., INTERNET, CAMERA, READ_CONTACTS)
Using reflection to access private class members in a restricted module

How to Fix It

Read the full exception message — it usually states exactly what operation was blocked.

Example: SecurityException: Permission denied: java.io.FilePermission '/etc/passwd' read
On Android, add the missing permission to your AndroidManifest.xml file.

Example: <uses-permission android:name='android.permission.INTERNET' /> — then rebuild and reinstall the app.
If running in an app server (Tomcat, JBoss), check the server's security policy file.

You may need to add a grant block for your application in the java.policy file.
For module-system errors in Java 9+, add the --add-opens JVM flag for the required package.

Example: --add-opens java.base/java.lang=ALL-UNNAMED
If you control the environment and security is not a concern, you can run without a SecurityManager.

In Java 8: remove the -Djava.security.manager JVM flag. Note: SecurityManager was deprecated in Java 17 and removed in Java 24.

When to Call a Professional

If this appears in a corporate application server or Java EE environment, your server administrator controls the security policy. Contact them to request the required permission — do not try to disable the SecurityManager on a shared server.

Frequently Asked Questions

Is SecurityException the same as an Android permission error?

They are related but slightly different. On Android, missing manifest permissions throw SecurityException. In standard Java, it is thrown by the SecurityManager which enforces a policy file.

What is the Java SecurityManager?

The SecurityManager is a Java class that intercepts sensitive operations. It checks each operation against a policy and throws SecurityException if it is not allowed. It was deprecated in Java 17 and removed in Java 24.

How do I check what Android permissions my app has declared?

Open your AndroidManifest.xml file in your project. All <uses-permission> tags near the top are the permissions your app requests. Missing a permission here will always cause a SecurityException at runtime.