If you have encountered errors or other problems when installing and starting LabKey Server, first review the topic Troubleshooting: Common Issues. If you're still encountering problems, please review the list below for common errors, messages, and problems.

You can also search the LabKey Community Support Forums for guidance. If you don't already see your issue listed there, please post a new question.



The LabKey Windows Graphical Installer hangs or fails while attempting to install PostgreSQL. You may see various PostgreSQL related errors such as:

  • Failed to start LabKey_pgsql-9.2...Unable to recover. The installer will now exit.
  • A service Labkey_pgsql-9.2 already exists. Please specify another name.

You can only install one instance of PostgreSQL on your computer at a time.

The PostgreSQL installer also has some conflicts with some antivirus or firewall software programs.

  • If you want to use the LabKey Windows Graphical Installer, uninstall PostgreSQL manually before beginning the LabKey install process.
  • If you already have PostgreSQL installed for another purpose, LabKey can use your installed instance; however, you will need to install LabKey manually. See Manual Installation for more information. 
  • If you have uninstalled a previous installation of LabKey Server, you may need to manually delete the PostgreSQL data directory in order to reinstall.
  • You may need to disable your antivirus or firewall software before running the LabKey installer, (see http://pginstaller.projects.postgresql.org/faq/FAQ_windows.html for more information).
  • On Windows you may need to remove references to Cygwin from your Windows system path before installing LabKey, due to conflicts with the PostgreSQL installer (see http://pginstaller.projects.postgresql.org/faq/FAQ_windows.html for more information).
  • If you are upgrading an existing LabKey server installation using the Windows Graphical Installer, have tried the above and still have problems installing PostgreSQL, you may need to manually stop a running LabKey_pgsql-## service.



Error on startup, "Connection refused. Check that the hostname and port are correct and that the postmaster is accepting TCP/IP connections."

ProblemTomcat cannot connect to the database.
Likely causes
  • The database is not running
  • The database connection URL or user credentials in the Tomcat configuration files are wrong
  • Tomcat was started before the database finished starting up
SolutionMake sure that database is started and fully operational before starting Tomcat. Check the database connection URL, user name, and password in the <tomcat>/conf/Catalina/localhost/labkey.xml file.


ErrorError when starting new LabKey Server installation, "PL/PgSQL not installed".
ProblemThis is a blocking error that will appear the first time you try to start LabKey Server on a fresh installation against PostgreSQL. It means that the database is working and that LabKey Server can connect to it, but that the Postgres command language, which is required for LabKey Server installation scripts, is not installed in PostgreSQL.
SolutionEnter the command <postfix>/bin/createlang plpgsql cpas, then shutdown and restart Tomcat.


ProblemError when connecting to LabKey server on Linux: Can't connect to X11 window server or Could not initialize class ButtonServlet.
SolutionRun tomcat headless. Edit tomcat's catalina.sh file, and add the following line near the top of the file:
Then restart tomcat.



After upgrading to building with Java 8, your server may still include some trunk code that was built with Java 7.


at sun.reflect.annotation.AnnotationParser.parseArray(AnnotationParser.java:532)
at sun.reflect.annotation.AnnotationParser.parseMemberValue(AnnotationParser.java:355)
at sun.reflect.annotation.AnnotationParser.parseAnnotation2(AnnotationParser.java:286)
at sun.reflect.annotation.AnnotationParser.parseAnnotations2(AnnotationParser.java:120)
at sun.reflect.annotation.AnnotationParser.parseAnnotations(AnnotationParser.java:72)
at java.lang.Class.createAnnotationData(Class.java:3521)
at java.lang.Class.annotationData(Class.java:3510)
at java.lang.Class.getAnnotation(Class.java:3415)
at org.labkey.api.action.SpringActionController$DefaultActionResolver$DefaultActionDescriptor.<init>(SpringActionController.java:908)
at org.labkey.api.action.SpringActionController$DefaultActionResolver$DefaultActionDescriptor.<init>(SpringActionController.java:893)
at org.labkey.api.action.SpringActionController$DefaultActionResolver.addAction(SpringActionController.java:848)
at org.labkey.api.action.SpringActionController$DefaultActionResolver.addInnerClassActions(SpringActionController.java:841)
at org.labkey.api.action.SpringActionController$DefaultActionResolver.<init>(SpringActionController.java:826)
at org.labkey.immport.ImmPortController.<clinit>(ImmPortController.java:72)


Use "gradlew cleanBuild deployApp" to build from scratch.



You receive a message "The requested resource () is not available." OR "500: Unexpected server error" and see something like one of the following in the log file:

SEVERE: Error deploying configuration descriptor labkey.xml 
java.lang.IllegalStateException: ContainerBase.addChild: start: LifecycleException: start: : java.lang.UnsupportedClassVersionError: org/labkey/bootstrap/LabkeyServerBootstrapClassLoader : Unsupported ...
A failure occurred during LabKey Server startup.
java.lang.NoClassDefFoundError: javax/script/ScriptEngineFactory....
A failure occurred during LabKey Server startup.
java.lang.UnsupportedClassVersionError: Bad version number in .class file
       at java.lang.ClassLoader.defineClass1(Native Method)
       at java.lang.ClassLoader.defineClass(ClassLoader.java:675) ...

You may need to be using a newer version of the JDK.  See Install Required Components.

Confirm that Tomcat is configured to use the correct version of Java, as it is possible to have multiple versions installed simultaneously.



Fatal Error in Java Runtime Environment

# A fatal error has been detected by the Java Runtime Environment:
# SIGSEGV (0xb) at pc=0x0000000000000000, pid=23893, tid=39779
# JRE version: Java(TM) SE Runtime Environment (8.0_45-b14) (build 1.8.0_45-b14)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (25.45-b02 mixed mode bsd-amd64 compressed oops)
# Problematic frame:
# C 0x0000000000000000
# Failed to write core dump. Core dumps have been disabled.
# To enable core dumping, try "ulimit -c unlimited" before starting Java again

These are typically bugs in the Java Virtual Machine itself.


Ensuring that you are on the latest patched release for your preferred Java version is best practice for avoiding these errors. If you have multiple versions of Java installed, be sure that JAVA_HOME and other configuration is pointing at the correct location. If you are running through the debugger in IntelliJ, check the JDK configuration: under Project Structure > SDKs check the JDK home path and confirm it points to the newer version.


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