ImagickExceptions in nextcloud.log

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You are in trouble with previews and/or with thumbnails within your Nextcloud?

You found errors like “ImagickException: not authorized…” in your Nextcloud logfile (/var/nc_data/nextcloud.log)?

Just follow these instructions in your terminal session (e.g. ssh) and solve these “Imagick” issues yourself:

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Error messages e.g.:

tail -f /var/nc_data/nextcloud.log | grep -i imagickexception

...
...ImagickException: not authorized `/upload_tmp/oc_tmp_zCg8T6-.d1539116135' @ error/constitute.c/ReadImage/412
...ImagickException: not authorized `/upload_tmp/oc_tmp_BiLdF7-.pdf' @ error/constitute.c/ReadImage/412
...

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Solution 1:

sudo -s (or su -)
apt install ghostscript -y
ln -s /usr/local/bin/gs /usr/bin/gs
cp /etc/ImageMagick-6/policy.xml /etc/ImageMagick-6/policy.xml.bak
sed -i "s/rights\=\"none\" pattern\=\"PS\"/rights\=\"read\|write\" pattern\=\"PS\"/" /etc/ImageMagick-6/policy.xml
sed -i "s/rights\=\"none\" pattern\=\"EPI\"/rights\=\"read\|write\" pattern\=\"EPI\"/" /etc/ImageMagick-6/policy.xml
sed -i "s/rights\=\"none\" pattern\=\"PDF\"/rights\=\"read\|write\" pattern\=\"PDF\"/" /etc/ImageMagick-6/policy.xml
sed -i "s/rights\=\"none\" pattern\=\"XPS\"/rights\=\"read\|write\" pattern\=\"XPS\"/" /etc/ImageMagick-6/policy.xml
service php7.3-fpm restart && service nginx restart

Solution 2 (necessary on DEBIAN 9.5 only so far?!):

su -
apt install ghostscript -y
ln -s /usr/local/bin/gs /usr/bin/gs
cp /etc/ImageMagick-6/policy.xml /etc/ImageMagick-6/policy.xml.bak && vi /etc/ImageMagick-6/policy.xml

add the following four rows to the end of the file before the </policymap>:

[...]
<policy domain="coder" rights="read|write" pattern="PS" />
<policy domain="coder" rights="read|write" pattern="EPI" />
<policy domain="coder" rights="read|write" pattern="PDF" />
<policy domain="coder" rights="read|write" pattern="XPS" />
</policymap>

Then restart all services:

service php7.3-fpm restart && service nginx restart

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Enjoy your personal data in your secured and hardened Nextcloud.

Don’t forget to backup your Nextcloud

Find more instructions here: Nextcloud Backup and Restore

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Carsten Rieger