Arc diff throws Runtime Exception mb_check_encoding() on windows


I updated the arcanist version on the clients - windows - pc yesterday (29.04.2020). So the version is:
arcanist 6ec09b2f482a6e6855c32da045b97d698db36aef (28 Apr 2020)

This is also a continuation of Arc lint hangs / does not terminate for cppcheck / cpplint

After upgrading arcanist, the arc diff command fails with the following error:

[2020-04-30 06:10:34] EXCEPTION: (RuntimeException) mb_check_encoding(): Input is something other than scalar or array at [\src\error\PhutilErrorHandler.php:263]
arcanist(head=master, ref.master=6ec09b2f482a)
#0 PhutilErrorHandler::handleError(integer, string, string, integer, array)
#1 mb_check_encoding(TempFile, string) called at [\src\utils\utf8.php:99]
#2 phutil_is_utf8(TempFile) called at [\src\xsprintf\PhutilCommandString.php:126]
#3 PhutilCommandString::escapeWindows(TempFile) called at [\src\xsprintf\PhutilCommandString.php:63]
#4 PhutilCommandString::escapeArgument(TempFile, string) called at [\src\xsprintf\csprintf.php:118]
#5 xsprintf_command(array, string, integer, TempFile, integer) called at [\src\xsprintf\xsprintf.php:70]
#6 xsprintf(string, array, array) called at [\src\xsprintf\PhutilCommandString.php:47]
#7 PhutilCommandString::renderString(boolean) called at [\src\xsprintf\PhutilCommandString.php:32]
#8 PhutilCommandString::getMaskedString() called at [\src\xsprintf\PhutilCommandString.php:20]
#9 PhutilCommandString::__construct(array) called at [\src\xsprintf\csprintf.php:37]
#10 csprintf(string, TempFile) called at [\src\future\exec\PhutilExecutableFuture.php:28]
#11 PhutilExecutableFuture::__construct(string, TempFile)
#12 ReflectionClass::newInstanceArgs(array) called at [\src\utils\utils.php:795]
#13 newv(string, array) called at [\src\repository\api\ArcanistGitAPI.php:23]
#14 ArcanistGitAPI::buildLocalFuture(array) called at [\src\repository\api\ArcanistRepositoryAPI.php:407]
#15 ArcanistRepositoryAPI::execxLocal(string, TempFile) called at [\src\repository\api\ArcanistGitAPI.php:820]
#16 ArcanistGitAPI::doCommit(string) called at [\src\workflow\ArcanistWorkflow.php:1252]
#17 ArcanistWorkflow::requireCleanWorkingCopy() called at [\src\workflow\ArcanistDiffWorkflow.php:716]
#18 ArcanistDiffWorkflow::runDiffSetupBasics() called at [\src\workflow\ArcanistDiffWorkflow.php:425]
#19 ArcanistDiffWorkflow::run() called at [\scripts\arcanist.php:411]

This seems to be a php error. I am not an php expert - but the bug is reported here:

The php version on the clients pc is:

PHP 7.3.3 (cli) (built: Mar 6 2019 21:53:23) ( ZTS MSVC15 (Visual C++ 2017) x64 )
Copyright © 1997-2018 The PHP Group
Zend Engine v3.3.3, Copyright © 1998-2018 Zend Technologies

Would a new installation of the released php version (7.45) fix this issue?
Thanks for your help

Updating php to Version 7.45 fixes this issue!

Thanks! I filed this upstream as

I think it should now be fixed by, which is available in master and stable.

(Upgrading PHP works, too.)