Unable to view thumbnails after install confluence server
Asked by jipuying:

Hi,everyone!

I have already finished installing atlassian-confluence-6.15.2-x64 on the server and my being-installed Mysql version is 14.14 distribution 5.7.25 for Linux(x86_64).

What's more, the java version is jre1.8.0_211.

The error shows that it could not initialize class com.atlassian.plugins.conversion.convert.image.ImagingConverter.

Below is the confluence_start_log on the server.

```

Server startup logs are located in /home/confluence/atlassian/confluence/logs/catalina.out
---------------------------------------------------------------------------
Using Java: /usr/lib/jvm3/jre1.8.0_211//bin/java
2019-05-20 09:17:29,001 INFO [main] [atlassian.confluence.bootstrap.SynchronyProxyWatchdog] A Context element for ${confluence.context.path}/synchrony-proxy is found in /home/confluence/atlassian/confluence/conf/server.xml. No further action is required
---------------------------------------------------------------------------
Using CATALINA_BASE: /home/confluence/atlassian/confluence
Using CATALINA_HOME: /home/confluence/atlassian/confluence
Using CATALINA_TMPDIR: /home/confluence/atlassian/confluence/temp
Using JRE_HOME: /usr/lib/jvm3/jre1.8.0_211/
Using CLASSPATH: :/home/confluence/atlassian/confluence/confluence/WEB-INF/atlassian-bundled-plugins/document-conversion-library-2.0.11.jar:/home/confluence/atlassian/confluence/bin/bootstrap.jar:/home/confluence/atlassian/confluence/bin/tomcat-juli.jar
Using CATALINA_PID: /home/confluence/atlassian/confluence/work/catalina.pid
Tomcat started.
```

And below is set_jre.sh on the server

```
JAVA_HOME="/usr/lib/jvm3/jre1.8.0_211/"; export JAVA_HOME #what we change to use local java
# Make sure prerequisite environment variables are set
if [ -z "$JAVA_HOME" -a -z "$JRE_HOME" ]; then
if $darwin; then
 # Bugzilla 54390
if [ -x '/usr/libexec/java_home' ] ; then
export JAVA_HOME=`/usr/libexec/java_home`
# Bugzilla 37284 (reviewed).
elif [ -d "/System/Library/Frameworks/JavaVM.framework/Versions/CurrentJDK/Home" ]; then
export JAVA_HOME="/System/Library/Frameworks/JavaVM.framework/Versions/CurrentJDK/Home"
fi
else
JAVA_PATH=`which java 2>/dev/null`
if [ "x$JAVA_PATH" != "x" ]; then
JAVA_PATH=`dirname $JAVA_PATH 2>/dev/null`
JRE_HOME=`dirname $JAVA_PATH 2>/dev/null`
fi
if [ "x$JRE_HOME" = "x" ]; then
# XXX: Should we try other locations?
if [ -x /usr/bin/java ]; then
JRE_HOME=/usr
fi
fi
fi
fi
if [ -z "$JRE_HOME" ]; then
JRE_HOME="$JAVA_HOME"
fi
#JRE_HOME="/home/confluence/atlassian/confluence/jre/"; export JRE_HOME #original version
```

Below is our atlassian-confluence log and the error shown with the could not initialize class com.atlassian.plugins.conversion.convert.image.ImagingConverter.

```
2019-05-17 13:13:34,200 ERROR [http-nio-9091-exec-4] [common.error.jersey.ThrowableExceptionMapper] toResponse Uncaught exception thrown by REST service: Could not initialize class com.atlassian.plugins.conversion.convert.image.ImagingConverter
-- referer: http://172.29.169.30:9091/display/SW/vgw?preview=%2F2588704%2F4161548%2Fimage.png | url: /rest/files/1.0/files/content/2588704/byAttachmentIds | traceId: 71b808f6c8be90e4 | userName: admin
java.lang.NoClassDefFoundError: Could not initialize class com.atlassian.plugins.conversion.convert.image.ImagingConverter
at com.atlassian.confluence.plugins.conversion.impl.DefaultConversionManager.getConverters(DefaultConversionManager.java:156)
at com.atlassian.confluence.plugins.conversion.impl.DefaultConversionManager.isConvertible(DefaultConversionManager.java:134)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
```

I want to know if there is someone can help me to fix my problem.


Answers:
author: Juan Arias
body: Same error as for me after updating my entire environment with no luck:

\`\`\`

# java -version

<br />

java version "1.8.0_221"  
Java(TM) SE Runtime Environment (build 1.8.0_221-b11)  
Java HotSpot(TM) 64-Bit Server VM (build 25.221-b11, mixed mode)

# atlas-version

ATLAS Version: 8.0.16  
ATLAS Home: /Users/juanarics/Projects/Atlassian/atlassian-plugin-sdk-8.0.16  
ATLAS Scripts: /Users/juanarics/Projects/Atlassian/atlassian-plugin-sdk-8.0.16/bin  
ATLAS Maven Home: /Users/juanarics/Projects/Atlassian/atlassian-plugin-sdk-8.0.16/apache-maven-3.5.4  
AMPS Version: 8.0.2  
--------  
Executing: /Users/juanarics/Projects/Atlassian/atlassian-plugin-sdk-8.0.16/apache-maven-3.5.4/bin/mvn --version -gs /Users/juanarics/Projects/Atlassian/atlassian-plugin-sdk-8.0.16/apache-maven-3.5.4/conf/settings.xml  
Apache Maven 3.5.4 (1edded0938998edf8bf061f1ceb3cfdeccf443fe; 2018-06-17T20:33:14+02:00)  
Maven home: /Users/juanarics/Projects/Atlassian/atlassian-plugin-sdk-8.0.16/apache-maven-3.5.4  
Java version: 1.8.0_221, vendor: Oracle Corporation, runtime: /Users/juanarics/.jabba/jdk/1.8.221/Contents/Home/jre  
Default locale: en_ES, platform encoding: UTF-8  
OS name: "mac os x", version: "10.14.3", arch: "x86_64", family: "mac"

\`\`\`

Tested with atlas-debug, atlas-run-standalone, etc with no luck and checked all related modules to be enabled as per (<https://jira.atlassian.com/browse/CONFSERVER-52541>)

ATM no luck at all

Juan Arias

Comalatech