DateTime::createFromFormat fails randomly - centos7

Question

I used the following script to test something that failed in one of my Yii2 projects:
<?php
$microtime = microtime(true);
echo $microtime . PHP_EOL;
$now = DateTime::createFromFormat('U.u', $microtime);
if (!$now):
echo "DateTime::createFromFormat failed..." . PHP_EOL;
exit(1);
endif;
echo $now->format("m-d-Y H:i:s.u") . PHP_EOL;
And here are the results for a few back to back runs:
[test#my-dev-1 ~]$ php test.php
1665274706.459722
10-09-2022 00:18:26.459722
[test#my-dev-1 ~]$ php test.php
1665274708.4653969
DateTime::createFromFormat failed...
[test#my-dev-1 ~]$ php test.php
\1665274721.9026799
DateTime::createFromFormat failed...
[test#my-dev-1 ~]$ php test.php
1665274723.7216589
DateTime::createFromFormat failed...
[test#my-dev-1 ~]$ php test.php
1665274724.6398611
DateTime::createFromFormat failed...
[test#my-dev-1 ~]$ php test.php
1665274725.429971
10-09-2022 00:18:45.429971
[test#my-dev-1 ~]$ php test.php
1665274726.474606
10-09-2022 00:18:46.474606
[test#my-dev-1 ~]$ php test.php
1665274727.37256
10-09-2022 00:18:47.372560
[test#my-dev-1 ~]$ php test.php
1665274728.3463521
DateTime::createFromFormat failed...
[test#my-dev-1 ~]$ php test.php
1665274729.4645841
DateTime::createFromFormat failed...
[test#my-dev-1 ~]$ php test.php
1665274730.809057
10-09-2022 00:18:50.809057
Server (CentOS Linux release 7.9.2009 (Core)) with the following PHP version:
PHP 7.4.32 (cli) (built: Sep 28 2022 09:09:55) ( NTS )
Why is DateTime::createFromFormat failing in some instances and in others it just works fine?

Answer 1

As per https://bugs.php.net/bug.php?id=64414 it seems like PHP internally can only handle %.6F values. As soon as more digits are supplied it will error out.
for ($i = 1; $i < 51; $i++){
$microtime = sprintf("%.6F", microtime(true));
echo $microtime . PHP_EOL;
$now = DateTime::createFromFormat('U.u', $microtime);
if (!$now):
echo "DateTime::createFromFormat failed..." . PHP_EOL;
exit(1);
endif;
echo $now->format("m-d-Y H:i:s.u") . PHP_EOL;
}
This version of the test script isn't failing any more.