ProGuard Troubleshooting

## Troubleshooting

While preparing a configuration for processing your code, you may bump into a few problems. The following sections discuss some common issues and solutions:

- Problems while processing
- Unexpected observations after processing
- Problems while preverifying for Java Micro Edition
- Problems at run-time

## Problems while processing

ProGuard may print out some notes and non-fatal warnings:

Note: ... calls '(...)Class.forName(variable).newInstance()'
  ProGuard lists all class casts of dynamically created class instances, like "`(MyClass)Class.forName(variable).newInstance()`". Depending on your application, you may need to keep the mentioned classes with an option like "`-keep class MyClass`", or their implementations with an option like "`-keep class * implements MyClass`". You can switch off these notes by specifying the `-dontnote` option.
Note: ... accesses a field/method '...' dynamically
  ProGuard lists a number of constructs like "`.getField("myField")`". Depending on your application, you may need to figure out where the mentioned class members are defined and keep them with an option like "`-keep class MyClass { MyFieldType myField; }`". You can switch off these notes by specifying the `-dontnote` option.
Note: duplicate definition of program/library class
  Your program jars or library jars contain multiple definitions of the listed classes. ProGuard continues processing as usual, only considering the first definitions. The warning may be an indication of some problem though, so it's advisable to remove the duplicates. A convenient way to do so is by specifying filters on the input jars or library jars. You can switch off these notes by specifying the `-dontnote` option.
Warning: can't write resource ... Duplicate zip entry
  Your input jars contain multiple resource files with the same name. ProGuard continues copying the resource files as usual, skipping any files with previously used names. Once more, the warning may be an indication of some problem though, so it's advisable to remove the duplicates. A convenient way to do so is by specifying filters on the input jars. There is no option to switch off these warnings.

ProGuard may terminate when it encounters parsing errors or I/O errors, or some more serious warnings:

Warning: can't find superclass or interface
  If there are unresolved references to superclasses or interfaces, you most likely forgot to specify an essential library. All libraries that are referenced by your code should be specified, including the Java run-time library. For specifying libraries, use the `-libraryjars` option.

  If the class that is reported as missing is a non-public library class, you should specify the `-dontskipnonpubliclibraryclasses` option. A common example is the class `java.util.zip.ZipConstants`, which is used as an interface class in some public classes, even though it is only package visible (in this case, the warning could also be ignored, because the class is not a fundamental part of the class hierarchy).

  If you're missing a library and you're absolutely sure it isn't used anyway, you can try your luck with the `-ignorewarnings` option, or even the `-dontwarn` option.

Warning: can't find referenced field/method
  If there are unresolved references to class members in input classes, your class files are most likely inconsistent. Possibly, some class file didn't get recompiled properly, or some class file was left behind after its source file was removed. Try removing all class files, recompiling them, zipping them up, and running ProGuard again.

  If the class member that is reported as missing is actually implemented in a non-public library class, you should specify the `-dontskipnonpubliclibraryclasses` option. A common example is the method `setLength(int)` in the public class `java.lang.StringBuilder`. This method is actually defined in the package visible superclass `java.lang.AbstractStringBuilder`, which ProGuard ignores by default.

  If your program classes reside in the same packages as library classes, and refer to their package visible class members, then you should specify the `-dontskipnonpubliclibraryclassmembers` option.

Warning: can't find enclosing class/method
  If there are unresolved references to classes that are defined inside methods in your input, once more, your class files are most likely inconsistent. Possibly, some class file didn't get recompiled properly, or some class file was left behind after its source file was removed. Try removing all class files, recompiling them, zipping them up, and running ProGuard again.
Warning: class file ... unexpectedly contains class ...
  The given class file contains a definition for the given class, but the directory name of the file doesn't correspond to the package name of the class. ProGuard will accept the class definition, but the current implementation will not write out the processed version. Please make sure your input classes are packaged correctly. Notably, class files that are in the `WEB-INF/classes` directory in a war should be packaged in a jar and put in the `WEB-INF/lib` directory. If you don't mind these classes not being written to the output, you can specify the `-ignorewarnings` option, or even the `-dontwarn` option.
Warning: ... is not being kept as ..., but remapped to ...
  There is a conflict between a `-keep` option in the configuration, and the mapping file, in the obfuscation step. The given class name or class member name can't be kept by its original name, as specified in the configuration, but it has to be mapped to the other given name, as specified in the mapping file. You should adapt your configuration or your mapping file to remove the conflict. Alternatively, if you're sure the renaming won't hurt, you can specify the `-ignorewarnings` option, or even the `-dontwarn` option.
Warning: field/method ... can't be mapped to ...
  There is a conflict between some new program code and the mapping file, in the obfuscation step. The given class member can't be mapped to the given name, because it would conflict with another class member that is already being mapped to the same name. This can happen if you are performing incremental obfuscation, applying an obfuscation mapping file from an initial obfuscation step. For instance, some new class may have been added that extends two existing classes, introducing a conflict in the name space of its class members. If you're sure the class member receiving another name than the one specified won't hurt, you can specify the `-ignorewarnings` option, or even the `-dontwarn` option. Note that you should always use the `-useuniqueclassmembernames` option in the initial obfuscation step, in order to reduce the risk of conflicts.
Error: You have to specify '-keep' options
  You either forgot to specify `-keep` options, or you mistyped the class names. ProGuard has to know exactly what you want to keep: an application, an applet, a servlet, a midlet,..., or any combination of these. Without the proper seed specifications, ProGuard would shrink, optimize, or obfuscate all class files away.
Error: Can't read [.../lib/rt.jar] (No such file or directory) (in MacOS X)
  In MacOS X, the run-time classes may be in a different place than on most other platforms. You'll then have to adapt your configuration, replacing the path `<java.home>/lib/rt.jar` by `<java.home>/../Classes/classes.jar`.

Should ProGuard crash while processing your application:

OutOfMemoryError
  You can try increasing the heap size of the Java virtual machine (with the usual `-Xms` and `-Xmx` options). You can also reduce the amount of memory that ProGuard needs by removing unnecessary library jars from your configuration, or by filtering out unused library packages and classes. Remember that only classes or interfaces that are extended or implemented by classes in your input jars are required.
StackOverflowError
  This error may occur when optimizing very complex methods on Windows (surprisingly, not so easily on Linux). You can always work around it by using ProGuard's `-dontoptimize` option. In theory, increasing the stack size of the Java virtual machine (with the usual `-Xss` option) should help too. In practice however, the `-Xss` setting doesn't have any effect on the main thread, due to Sun Bug #4362291. As a result, this solution will only work when running ProGuard in a different thread, e.g. from its GUI.
Otherwise...
  Maybe your class files are corrupt. See if recompiling them and trying again helps. If not, please report the problem, preferably with the simplest example that causes ProGuard to crash.

## Unexpected observations after processing

If ProGuard seems to run fine, but your processed code doesn't look right, there might be a couple of reasons:

Disappearing classes
  If you are working on Windows and it looks like some classes have disappeared from your output, you should make sure you're not writing your output class files to a directory (or unpacking the output jar). On platforms with case-insensitive file systems, such as Windows, unpacking tools often let class files with similar lower-case and upper-case names overwrite each other. If you really can't switch to a different operating system, you could consider using ProGuard's `-dontusemixedcaseclassnames` option.

  Also, you should make sure your class files are in directories that correspond to their package names. ProGuard will read misplaced class files, but it will currently not write their processed versions. Notably, class files that are in the `WEB-INF/classes` directory in a war should be packaged in a jar and put in the `WEB-INF/lib` directory.

Classes or class members not being kept
  If ProGuard is not keeping the right classes or class members, make sure you are using fully qualified class names. If the package name of some class is missing, ProGuard won't match the elements that you might be expecting. It may help to double-check for typos too. You can use the `-printseeds` option to see which elements are being kept exactly.

  If you are using marker interfaces to keep other classes, the marker interfaces themselves are probably being removed in the shrinking step. You should therefore always explicitly keep any marker interfaces.

Variable names not being obfuscated
  If the names of the local variables and parameters in your obfuscated code don't look obfuscated, because they suspiciously resemble the names of their types, it's probably because the decompiler that you are using is coming up with those names. ProGuard's obfuscation step does remove the original names entirely, unless you explicitly keep the `LocalVariableTable` or `LocalVariableTypeTable` attributes.

## Problems while preverifying for Java Micro Edition

If ProGuard seems to run fine, but the external preverifier subsequently produces errors, it's usually for a single reason:

InvalidClassException, class loading error, or verification error
  If you get any such message from the preverifier, you are probably working on a platform with a case-insensitive file system, such as Windows. The `preverify` tool always unpacks the jars, so class files with similar lower-case and upper-case names overwrite each other. You can use ProGuard's `-dontusemixedcaseclassnames` option to work around this problem.

  If the above doesn't help, there is probably a bug in the optimization step of ProGuard. Make sure you are using the latest version. You should be able to work around the problem by using the `-dontoptimize` option. You can check the bug database to see if it is a known problem (often with a fix). Otherwise, please report it, preferably with the simplest example on which you can find ProGuard to fail.

Note that it is no longer necessary to use an external preverifier. With the `-microedition` option, ProGuard will preverify the class files for Java Micro Edition.

## Problems at run-time

If ProGuard runs fine, but your processed application doesn't work, there might be several reasons:

Stack traces without class names or line numbers
  If your stack traces don't contain any class names or lines numbers, even though you are keeping the proper attributes, make sure this debugging information is present in your compiled code to start with. Notably the Ant javac task has debugging information switched off by default.
NoClassDefFoundError
  Your class path is probably incorrect. It should at least contain all library jars and, of course, your processed program jar.
ClassNotFoundException
  Your code is probably calling `Class.forName`, trying to create the missing class dynamically. ProGuard can only detect constant name arguments, like `Class.forName("mypackage.MyClass")`. For variable name arguments like `Class.forName(someClass)`, you have to keep all possible classes using the `-keep` option, e.g. "`-keep class mypackage.MyClass`" or "`-keep class * implements mypackage.MyInterface`".
NoSuchMethodException
  Your code is probably calling something like `myClass.getMethod`, trying to find some method dynamically. Since ProGuard isn't detecting this (yet), you have to keep the missing method in using the `-keep` option, e.g. "`-keep class mypackage.MyClass { void myMethod(); }`".
MissingResourceException or NullPointerException
  Your processed code may be unable to find some resource files. ProGuard currently simply copies resource files over from the input jars to the output jar. Their names and contents remain unchanged. If a class looks for a resource file in its directory, this will fail if the package name of the class has changed. You should then keep the class name, with the `-keepnames` option. Also note that directory entries in jar files aren't copied at all.
Invalid or corrupt jarfile
  You are probably starting your application with the java option `-jar` instead of the option `-classpath`. The java virtual machine returns with this error message if your jar doesn't contain a manifest file (`META-INF/MANIFEST.MF`), if the manifest file doesn't specify a main class (`Main-Class:` ...), or if the jar doesn't contain this main class. You should then make sure that the input jar contains a valid manifest file to start with, that this manifest file is the one that is copied (the first manifest file that is encountered), and that the main class is kept in your configuration,
InvalidClassException, class loading error, or verification error (in Java Micro Edition)
  If you get such an error in Java Micro Edition, you may have forgotten to specify the `-microedition` option, so the processed class files are preverified properly.
Failing midlets (in Java Micro Edition)
  If your midlet simply won't start, you might try using the `-dontusemixedcaseclassnames` option. Even if it has been properly processed and then preverified on a case-sensitive file system, the device itself might not like the mixed-case class names. Notably, the Nokia N-Gage emulator works fine, but the actual device seems to exhibit this problem.
SecurityException: SHA1 digest error
  You may have forgotten to sign your program jar after having processed it with ProGuard.
ClassCastException: class not an enum
  You are probably processing enumeration types and calling `EnumSet.allOf`. You should then make sure you're preserving the `values()` method of the enumeration type, as shown in the examples.
ArrayStoreException: sun.reflect.annotation.EnumConstantNotPresentExceptionProxy
  You are probably processing annotations involving enumerations. Again, you should make sure you're preserving the `values()` method of the enumeration type, as shown in the examples.
Error: No Such Field or Method, Error verifying method (in a Java Micro Edition emulator)
  If you get such a message in a Motorola or Sony Ericsson phone emulator, it's because these emulators don't like packageless classes and/or overloaded fields and methods. You can work around it by not using the options -repackageclasses '' and -overloadaggressively. If you're using the JME WTK plugin, you can adapt the configuration `proguard/wtk/default.pro` that's inside the `proguard.jar`.
CompilerError: duplicate addition
  You are probably compiling or running some code that has been obfuscated with the `-overloadaggressively` option. This option triggers a bug in `sun.tools.java.MethodSet.add` in Sun's JDK 1.2.2, which is used for (dynamic) compilation. You should then avoid this option.
ClassFormatError: repetitive field name/signature
  You are probably processing some code that has been obfuscated before with the `-overloadaggressively` option. You should then use the same option again in the second processing round.
NoSuchMethodError or AbstractMethodError
  Again, you should make sure you're not writing your output class files to a directory on a platform with a case-insensitive file system, such as Windows. Please refer to the first item on this list for details.

  Furthermore, you should check whether you have specified your program jars and library jars properly. Program classes can refer to library classes, but not the other way around.

  If all of this seems ok, perhaps there's a bug in ProGuard (gasp!). If so, please report it, preferably with the simplest example on which you can find ProGuard to fail.

VerifyError
  Verification errors when executing a program are almost certainly the result of a bug in the optimization step of ProGuard. Make sure you are using the latest version. You should be able to work around the problem by using the `-dontoptimize` option. You can check the bug database to see if it is a known problem (often with a fix). Otherwise, please report it, preferably with the simplest example on which you can find ProGuard to fail.