Good morning 
I hope u all okay and doing fine.
Version 3.25.20+210330   is the version that I use,
I have 10571 responses on my survey, when I try to export it all at once it gives me a web page with an error,
the message is 
This page isn’t working 

---

 is currently unable to handle this request.
HTTP ERROR 500

in addition, when I export the responses as two pieces (for example from 7000 to 14000 responses and from 14001 to 10751 then it works normally), so, I think the error returns to the huge number of the survey responses.
how can i solve this issue.

This is a server issue, you need to look at your settings of the server, especially exectution time for PHP scripts, as well as max_vars and the file size allowed. But this has very little to do with Limesurvey, this is a server configuration issue that only you / your server administrator can solve.

thanks for your help Mr holch.