Emails not sent WP 5.7 and PhP 7.4, FD_SETSIZE problem?

Hi,

I recently upgraded to WP 5.7. running on php 7.4. I went to setup SMTP but that gave the error below. Seems that FD_SETSIZE is too small.

I only solved the problem by downgrading to php 7.3.

Has anybody had the same issue?

Cheers,

Steffen

021-03-16 00:54:24 Connection: opening to XXX.mailout.server-he.de:587, timeout=300, options=array ( ‘ssl’ => array ( ‘verify_peer’ => false, ‘verify_peer_name’ => false, ‘allow_self_signed’ => true, ),)

2021-03-16 00:54:24 Connection: opened

2021-03-16 00:54:24 Connection failed. Error #2: stream_select(): You MUST recompile PHP with a larger value of FD_SETSIZE.It is set to 1024, but you have descriptors numbered at least as high as 1318. –enable-fd-setsize=2048 is recommended, but you may want to set itto equal the maximum number of open files supported by your system,in order to avoid seeing this error again at a later date. [/is/htdocs/XXX/wp-includes/PHPMailer/SMTP.php line 1225]

2021-03-16 00:59:24 SMTP -> get_lines(): select timed-out in (300 sec)

2021-03-16 00:59:24 SERVER -> CLIENT:

2021-03-16 00:59:24 Connection: closing due to error

2021-03-16 00:59:24 Connection: closed

SMTP connect() failed.