Yes it are different PHP versions.
The Linux one is php-fpm 8.1.
XAMPP is php 7.4
By the way another problem popped up. It is not as "critical" as the export one. I have noticed now that the "Import" function to import archived projects, no longer works. It did work in XOT 3.10.
The upload limit is 50 MB. The zip file is approximately 35 MB.
The apache2 error.log has the following entry after trying to do an import of the file Creo_8_archive.zip
[Sun Mar 05 21:57:56.060048 2023] [proxy_fcgi:error] [pid 38235:tid 139636555216640] [client xxx.xxx.xxx.xxx:63984] AH01071: Got error 'PHP message: PHP Warning: ini_set(): Session ini settings cannot be changed when a session is active in /var/www/xerte/config.php on line 262PHP message: PHP Notice: session_start(): Ignoring session_start() because a session is already active in /var/www/xerte/config.php on line 263PHP message: Unable to move uploaded project file to imported file: From: To: /var/www/xerte/import/435378056/1678049876Creo_8_archive.zip', referer: https://myserver/xerte/workspaceproperties.php
Based on what you wrote, I have done some additional testing and I have finally found the cause.
You mentioned before the default upload was 2 MB. I had changed the php.ini file for fpm (upload_max_filesize = 50M). I started to wonder whether this was the only setting that was needed. So I have added LimitRequestBody 52428800 (which means the maximum upload size is 50M) to the site configuration in Apache2. This made no difference. Then I thought perhaps the php code is executed through cgi or cli. So I changed the php.ini for cgi and cli so that it also contained the setting upload_max_filesize = 50M. This solved the problem.
Thank you very much for helping me solve my problem.