java.lang.UnsatisfiedLinkError: no dll in java.library.path - Cause and Solution

"Exception in thread "main" java.lang.UnsatisfiedLinkError: no dll in java.library.path" is one of the frustrating errors you will get if your application is using native libraries like the DLL in Windows or .SO files in Linux. Java loads native libraries at runtime from either PATH environment variable or location specified by java.library.path system property depending upon whether your Java program is using System.load() or java.lang.System.loadLibarray() method to load native libraries. If Java doesn't find them due to any reason it throws "java.lang.UnsatisfiedLinkError: no dll in java.library.path". 

Some of the most common UnsatisfiedLinkError is "java.lang.UnsatisfiedLinkError: no ocijdbc10.dll in java.library.path" and "java.lang.UnsatisfiedLinkError: no ocijdbc11.dll in java.library.path", which comes when you try to connect to Oracle 10g or 11g database from Java program using OCI JDBC driver.

If you write games in Java program using lwjgl then you might have seen this error as well "java.lang.unsatisfiedlinkerror no lwjgl in java.library.path", which comes when Java doesn't find a native component of the lwjgl.jar library. It also common on Java application which uses JNI to link some core legacy libraries in C and C++.   

I first encountered this error while writing some Tibco Rendezvous Messaging code which uses some windows specific dll, which is installed as part of the TIBCO RV installation. I was getting "java.lang.UnsatisfiedLinkError: Native library not found" which was caused by "java.lang.UnsatisfiedLinkError: no tibrvnative in java.library.path". 

I wasted a lot of hours playing with PATH, java.library.path, and others only to learn from experience. Here you will learn the root cause of "Exception in thread "main" java.lang.UnsatisfiedLinkError: no dll in java.library.path" and learn how to fix this Exception in Java.

Cause of java.lang.UnsatisfiedLinkError: no dll in java.library.path:

When you load native libraries like .so on Linux or .dll on Windows using System.loadLibrary() Java looks for those shared libraries in both PATH environment variable and java.library.path system property, If it doesn't find shared library it throws "Exception in thread "main" java.lang.UnsatisfiedLinkError: no XXX dll in java.library.path". 

Now trick is that in Windows it picks up dll from System32 folder and most of the time System32 exists in path so we don't usually come up with this problem, but this work only if program has put a copy of dll in that folder.

For example, the corporate installation of Tibco Rendezvous does put tibrvnative.dll in System 32 folder, but if you install let's say Oracle 10g or 11g, the native library ocijdbc11.dll is installed at custom location usually on ORACLE_HOME/bin directory. 

It also worth identifying is whether your application or third party library which is throwing this error like  Oracle JDBC driver is using System.load() or System.loadLibrary() method. 

You can also identify this by looking at the error message, if you see java.library.path in error message means it surely using System.loadLibrary(). This message also tells that program has provided that system property and the program is not looking for PATH for native libraries. 

Anyway if you are repeatedly getting this error then you can try following steps which may help you to resolve java.lang.UnsatisfiedLinkError in your Java application.

Solution of  "java.lang.UnsatisfiedLinkError: no dll in java.library.path"

As error clearly says that Java is not able to find some native library required, it could mean either library is not exists or Java is not able to locate them due to incorrect PATH or java.library.path. Remember, when you don't provide this system property, by default Java looks at PATH for native libraries in Windows operating system and on LD_LIBRARY_PATH in Linux. 

Though it's good practice to provide this PATH and use System.loadLibrary() method to have a consistent location for native libraries on all platforms. 

Here are a couple of things you can do to solve error "java.lang.UnsatisfiedLinkError: no dll in java.library.path" :

1. Check your PATH for Java, whether it contains required dll or not.

2. Verify your java.library.path in case you have set it for required dll.

3. Run your java application with command : java -Djava.library.path= "your dll path"

4. Try specifying a base name for the library and loading library using System.loadLibaray("name) where the name is without dll.

5. Linux loads dynamically linked library(.so) from LD_LIBRARY_PATH so you may want to have your shared library directory included in LD_LIBRARY_PATH e.g.

$ export LD_LIBRARY_PATH=/shared library (.so)

6. load library by providing absolute path like "C:/WINNT/system32/digest.dll" by using System.load("Path of native library") method. 

The main point is JVM should find your dll and providing an explicit path with -Djava.library.path always help me.

Still getting java.lang.UnsatisfiedLinkError

If you are still getting Exception in thread "main" java.lang.UnsatisfiedLinkError: no dll in java.library.path, even after adding JAR into classpath and adding the native library into PATH environment variable and providing system property java.library.path pointing to the location of native library location then there is must be some directory in your PATH which is not resolved correctly.

I was frustrated after trying every method to solve this error, when I noticed the following error, just before this error comes :

"The system cannot find the path specified" when I printed PATH variable.

since I was doing set PATH= %PATH%; (location of the native library)

The system was not able to navigate to that directory because of those non-existent paths. In order to solve that I just did opposite, added location of native library in front of PATH and it worked like a charm

$ set PATH = {location of native dll}; %PATH%

So pay attention to your PATH variable. It often happens PATH keeps directories of a uninstalled program which abruptly breaks and System stops searches further. This issue can also come in Linux and you can solve it just like this, add your native library as the first entry in PATH environment variable.

Now a bit of theory, if you use System.loadLibrary() then it searches native library in the location specified by java.library.path but if you don't provide that system library then it defaults to PATH environment variable.

Things to Remember 

Some other points worth noting while working with System dependent libraries:

1. They make Java code platform-dependent.

2. System.loadLibrary() is equivalent to Runtime.getRuntime.loadLibary().

3. load System.loadLibary(library) in static initializer block so that it only gets loaded when containing class gets loaded and avoid reloading of it, though it could also lead to ExceptionInitializerEror and NoClassDefFoundError if native libraries are not found. 

4. Another worth noting point is paying attention to exact error message java.lang.UnsatisfiedLinkError throws. if it shows  "Exception in thread "main" java.lang.UnsatisfiedLinkError: no dll in java.library.path"  means JVM is not able to locate and load library. if it shows thread "main" java.lang.UnsatisfiedLinkError: com......' i.e. prints class or method name then maybe something is wrong with the library itself like half copied dll.

Sometimes you may also get

Exception in thread "main" java.lang.UnsatisfiedLinkError: Expecting an absolute path of the library: digest.dll

        at java.lang.Runtime.load0(Runtime.java:767)

        at java.lang.System.load(System.java:1003)

to solve this just provide absolute path for library and you will be fine.

That’s all on how to fix  Exception in thread "main" java.lang.UnsatisfiedLinkError: no dll in java.library.path". I have shared all the information I know about UnsatisfiedLinkError in Java like what causes this error and how you can fix this error. I have spent countless hours to figuring out the solution but you can learn from my experience and avoid that. You can also share your experience if you have faced this java.lang.UnsatisfiedLinkError before.

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Thanks for reading this article. If this Java troubleshooting guide helped you to fix UnsatisifiedLinkError in your application, please share this with your friends. If you are still getting error and not able to solve, feel free to drop a note with details like what have you tried so far.