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Alternative 1: Modify the size of the uploaded PDFs so that they do not exceed 2 to 4 Mb. We have detected that the weight of the file is related to the preview problem, linked to the RAM of the affected computer. A PC with 8 megs will start having problems from 2 Mb file size. We recommend splitting PDFs into smaller files, there are many ways to break these files into smaller pieces or even compress them, an internet search will result in many different solutions to this.
Alternative 2: Publish as a link instead of using the File activity and upload the whole file. We will use this only if our PDF is one more activity in the learningCentral course. If it is documentation added to the library or to the course itself we recommend adding the link, not the file.
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