In T4752#177071, @cspeckmim wrote:

setfacl -Rdm u:phab-phd:rw /var/local/phabricator/filestore
setfacl -Rm u:phab-phd:rw /var/local/phabricator/filestore

Just ran into this issue on a freshly installed Ubuntu 16.04 docker container.
Actually it's just the package phpX.Y-xml what is missing.
In my case it was php7.2 so all I needed to do was:

sudo apt install php7.2-xml

(No extra repositories needed...)

For me it would be a great enhancement if there would be a shortcut which temporarily toggles this option:
Settings → Personal Settings → APPLICATIONS → Diff Preferences → Show Older Inlines

A small update on this topic.
The diff I have submitted above in P1853#4950 is not working anymore since rP45b386596e62.
The corrected patch would be:

--- a/InsecureRemarkupGraphvizBlockInterpreter.php      2016-02-24 08:47:54.517183033 +0000
+++ b/InsecureRemarkupGraphvizBlockInterpreter.php      2016-02-24 08:51:02.784873997 +0000
@@ -41,11 +41,14 @@
           $stderr));
     }

This happened to me yesterday too. I am using the stable branch. The only thing that changed that I upgraded git to the latest release 2.11.0.
I have tried to change to the master branch which did not solve the problem. The problem was solved then by downgrading git to 2.10.2.

I get the same issue after upgrading:

For everyone who would like to use this feature (Taking of course the above mentioned security risks into account).

@epriestley I see. Thanks anyways. Nevertheless I am hoping that some hints are available at buddy rates :)

@epriestley Thanks for the prompt answer. Isn't there any way to mark these preview files as temporary, or any maintenance task that I could run to remove all graphviz.png files that are not referenced from anywhere?

There is a problem I have stumbled upon.