This post is a possible fix to this errors:
ImageMagickContentTransformerWorker not available: 06020018
06020006 The content node was not specified so the content cannot be streamed to the client: classpath*:alfresco/templates/webscripts/org/alfresco/repository/thumbnail/thumbnail.get.js on WINx64
1º.- Modify setenv.bat:
set MAGICK_CONFIGURE_PATH=C:\alfresco-community\imagemagick\modules\coders
2º.- Modify alfresco-global.properties
img.root=C:/ALFRES~1/imagemagick
img.dyn=${img.root}/lib
img.exe=${img.root}/convert.exe
img.coders=${img.root}/modules/coders
img.config=${img.root}/config
#img.gslib=${img.root}/lib <- COMMENT THIS
3º.- Create 2 custom xml files in alfresco-community\tomcat\shared\classes\alfresco\extension
custom-alfresco-pdf-renderer-transform-context.xml
<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE beans PUBLIC '-//SPRING//DTD BEAN//EN' 'http://www.springframework.org/dtd/spring-beans.dtd'>
<beans>
<bean id="transformer.worker.subsys.alfresco-pdf-renderer" class="org.alfresco.repo.content.transform.pdfrenderer.AlfrescoPdfRendererContentTransformerWorker">
<property name="mimetypeService">
<ref bean="mimetypeService" />
</property>
<property name="executer">
<bean name="transformer.alfresco-pdf-renderer.command" class="org.alfresco.util.exec.RuntimeExec">
<property name="commandsAndArguments">
<map>
<entry key=".*">
<list>
<value>${alfresco-pdf-renderer.exe}</value>
<value>SPLIT:${options}</value>
<value>${source}</value>
<value>${target}</value>
</list>
</entry>
</map>
</property>
<property name="processProperties" ref="#{systemProperties['os.name'].contains('Windows') ? 'transformer.worker.subsys.alfresco-pdf-renderer.processPropertiesWindows' : 'transformer.worker.subsys.alfresco-pdf-renderer.processPropertiesUnix'}" />
<property name="defaultProperties">
<props>
<prop key="options"></prop>
</props>
</property>
<property name="errorCodes" >
<value>1</value>
</property>
</bean>
</property>
<property name="checkCommand">
<bean name="transformer.Pdfium.CheckCommand" class="org.alfresco.util.exec.RuntimeExec">
<property name="commandsAndArguments">
<map>
<entry key=".*">
<list>
<value>${alfresco-pdf-renderer.exe}</value>
<value>--version</value>
</list>
</entry>
</map>
</property>
</bean>
</property>
</bean>
<bean id="transformer.worker.subsys.alfresco-pdf-renderer.processPropertiesWindows" class="org.springframework.beans.factory.config.MapFactoryBean">
<property name="sourceMap">
<map>
<entry key="ALFRESCO-PDF-RENDERER_HOME">
<value>${alfresco-pdf-renderer.root}</value>
</entry>
</map>
</property>
</bean>
<bean id="transformer.worker.subsys.alfresco-pdf-renderer.processPropertiesUnix" class="org.springframework.beans.factory.config.MapFactoryBean">
<property name="sourceMap">
<map>
<entry key="ALFRESCO-PDF-RENDERER_HOME">
<value>${alfresco-pdf-renderer.root}</value>
</entry>
</map>
</property>
</bean>
</beans>
custom-imagemagick-transform-context.xml
<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE beans PUBLIC '-//SPRING//DTD BEAN//EN' 'http://www.springframework.org/dtd/spring-beans.dtd'>
<beans>
<bean id="transformer.worker.ImageMagick" class="org.alfresco.repo.content.transform.magick.ImageMagickContentTransformerWorker">
<property name="mimetypeService">
<ref bean="mimetypeService" />
</property>
<property name="executer">
<bean name="transformer.ImageMagick.Command" class="org.alfresco.util.exec.RuntimeExec">
<property name="commandsAndArguments">
<map>
<entry key=".*">
<list>
<value>${img.exe}</value>
<value>${source}</value>
<value>SPLIT:${options}</value>
<value>-strip</value>
<value>-quiet</value>
<value>${target}</value>
</list>
</entry>
</map>
</property>
<property name="processProperties" ref="#{systemProperties['os.name'].contains('Windows') ? 'transformer.worker.ImageMagick.processPropertiesWindows' : 'transformer.worker.ImageMagick.processPropertiesUnix'}" />
<property name="defaultProperties">
<props>
<prop key="options"></prop>
</props>
</property>
<property name="errorCodes" >
<!-- The published error and fatal error codes are in the 400 and 700 ranges, but 1 is the most common and have seen 255 (could that by -1) -->
<value>1,2,255,400,405,410,415,420,425,430,435,440,450,455,460,465,470,475,480,485,490,495,499,700,705,710,715,720,725,730,735,740,750,755,760,765,770,775,780,785,790,795,799</value>
</property>
</bean>
</property>
<property name="checkCommand">
<bean name="transformer.ImageMagick.CheckCommand" class="org.alfresco.util.exec.RuntimeExec">
<property name="commandsAndArguments">
<map>
<entry key=".*">
<list>
<value>${img.exe}</value>
<value>-version</value>
</list>
</entry>
</map>
</property>
</bean>
</property>
</bean>
<bean id="transformer.worker.ImageMagick.processPropertiesWindows" class="org.springframework.beans.factory.config.MapFactoryBean">
<property name="sourceMap">
<map>
<entry key="MAGICK_HOME">
<value>${img.root}</value>
</entry>
<entry key="MAGICK_CODER_MODULE_PATH">
<value>${img.coders}</value>
</entry>
<entry key="MAGICK_CONFIGURE_PATH">
<value>${img.config}</value>
</entry>
<entry key="DYLD_FALLBACK_LIBRARY_PATH">
<value>${img.dyn}</value>
</entry>
<entry key="LD_LIBRARY_PATH">
<value>${img.dyn}</value>
</entry>
</map>
</property>
</bean>
<bean id="transformer.worker.ImageMagick.processPropertiesUnix" class="org.springframework.beans.factory.config.MapFactoryBean">
<property name="sourceMap">
<map>
<entry key="MAGICK_HOME">
<value>${img.root}</value>
</entry>
<entry key="DYLD_FALLBACK_LIBRARY_PATH">
<value>${img.dyn}</value>
</entry>
<entry key="LD_LIBRARY_PATH">
<value>${img.dyn}</value>
</entry>
</map>
</property>
</bean>
</beans>
4º.- Restart TomcatServer
This fixed me the issue with thumbnails not working on Alfresco Community edition Windows 10 install (x64).
Let me know if it also works for you!