Error "session_start(): Ignoring session_start() because a session is already active"

Hello,

we got a weird issue on our DEV environnment ; the error message we got is "session_start(): Ignoring session_start() because a session is already active". Our dev is running under PHP 8.0.

This message is happening when a custom job tries to call, using External Resource Client, a external API.

The code was working when using CURL's call. We followed this article to transform our code : 

https://support.sugarcrm.com/Documentation/Sugar_Developer/Sugar_Developer_Guide_12.3/Integration/ExternalResourceClient/#Examples_of_Replacing_cURL

We do not open any session from our code ; we suppose this error is linked to the file_get_contents instruction (line 241) of 

src\Security\HttpClient\ExternalResourceClient.php

(but not for sure).

Any help, suggestion or whatever is welcome.

Fred