Arc Upgrade broke me

Ran the Arc Upgrade yesterday, and it broke everything. Any time I run an arc diff (any repo) I get this:

d:\Development\grader-common>arc diff ff416bab34f27bc24fcfb26b451cf741ae790373
Linting...
No lint engine configured for this project.
Running unit tests...
No unit test engine is configured for this project.
Exception
Call to "proc_open()" to open a subprocess failed: proc_open(): CreateProcess failed, error code - 2
COMMAND
file --brief --mime "C:\Users\Ryan\AppData\Local\Temp\9mbm0ulhyjwowkg4\366497.tmp"

STDOUT
(empty)

STDERR
(empty)
(Run with `--trace` for a full exception trace.)

Running in trace mode comes up with this:

STDERR
(empty) at [<arcanist>\src\future\exec\ExecFuture.php:641]
arcanist(head=master, ref.master=ee66b15bd469)
#0 ExecFuture::isReady() called at [<arcanist>\src\future\Future.php:37]
#1 Future::resolve() called at [<arcanist>\src\future\exec\execx.php:37]
#2 exec_manual(string, string) called at [<arcanist>\src\filesystem\Filesystem.php:635]
#3 Filesystem::getMimeType(string) called at [<arcanist>\src\workflow\ArcanistDiffWorkflow.php:2797]
#4 ArcanistDiffWorkflow::getFileMimeType(string) called at [<arcanist>\src\workflow\ArcanistDiffWorkflow.php:2736]
#5 ArcanistDiffWorkflow::uploadFilesForChanges(array) called at [<arcanist>\src\workflow\ArcanistDiffWorkflow.php:1126
]
#6 ArcanistDiffWorkflow::generateChanges() called at [<arcanist>\src\workflow\ArcanistDiffWorkflow.php:462]
#7 ArcanistDiffWorkflow::run() called at [<arcanist>\scripts\arcanist.php:411]
<<< [1] (+5,559) <exec> 5,559,657 us

Error code 2 is for file not found, and when I search for the temp directory/file I don’t come up with anything in explorer. Also, it’s weird, the temp file used in notepad++ is not the same one it’s erroring on.

Is there a way to downgrade or swich to the stable branch? I can’t start any diff’s for code that needs to released.

You can switch to stable by fetching and checking out the stable branch in arcanist/ and libphutil/:

arcanist/ $ git fetch origin stable
arcanist/ $ git checkout stable
libphutil/ $ git fetch origin stable
libphutil/ $ git checkout stable

I suspect the issue may be that the file binary does not exist on your system and you also don’t have any of the MIME detection extensions installed. We should handle this case more gracefully than we do, I’ll take a look at it.

Thank you for the quick reply.

Is there anything else I can provide to help to debug?

When I did the install, I followed the procedure detailed in the phabricator website. I’m running windows, so that may cause some problems I’m guessing. I’m running PHP version 7.3.12, and Windows 10 latest build.