Recently I tested my therory with a pdf which contains thumbnails and above error message didn't appear in log file. So whoever has marked prematurely as correct answer, he was wrong. 

Thanks for you answer. Based on your posted link and a youtube video I assume that uploaded pdf file does not contain any thumbnail images. I will test it with such pdf file with a thumbnail image and give a feedback.

Hello everyone, It's time form me to ask a new question :-):Whenever I create an assert from a pdf file, the following error occurs in error.log: [Thread-72] com.day.cq.dam.core.impl.ui.preview.FolderPreviewUpdaterImpl error while executing folder thumbnail update job: /content/dam/mypath/apdffile.p...

The css-Option does work, the js option not.

Thanks for your answer. I tried it as you suggested and it does not work either. Here the content of my .content.xml file: <?xml version="1.0" encoding="UTF-8"?><jcr:root xmlns:sling="http://sling.apache.org/jcr/sling/1.0" xmlns:cq="http://www.day.com/jcr/cq/1.0" xmlns:jcr="http://www.jcp.org/jcr/1....

Thanks for your answer.As you suggested I checked my Javascript at freeformatter.com and it showed me a couple of errors due tue modern language version of ES6. This compiler blamed mostly the word let.After that I looked at the internet what the abbreviation 'gcc' means. This stands for Google clos...

Thanks for your answer.I changed the configuration from languageIn=Javascript;languageOut=Javascript to languageIn=ECMASCRIPT_15;languageOut=ECMASCRIPT_15 and it doesn't still work. As you suggested I checked my Javascript at freeformatter.com and it showed me a couple of errors due tue modern langu...

Hello, I've got a request for minify css and javascript files on an AEM6.4 instance. My research in the Internet gave me following sources: https://experienceleague.adobe.com/docs/experience-cloud-kcs/kbarticles/KA-16544.html?lang=us-enhttps://experienceleague.adobe.com/docs/experience-manager-64/de...

I could find the path for AEM 6.4 this is "/libs/granite/ui/components/shell/page/page.jsp" . Though, thanks for your help leading me into right direction. Let's hope to find the right path for AEM 5.6 either.

Thanks for your answer. I have beeing investigating further and found /libs/cq/gui/components/authoring/editors/core/head.jsp as a source for the edit mode. The requirement got an specification for creating a dynamic title.