Can you enable debug = 2 in application/config/config.php and try again, please? Paste the complete error message here.

In the test environment, we have debugging = 2 enabled. But it only returns error 500 as in the screenshot. Unfortunately, I do not have access to SQL logs, and those on the PHP side do not return anything, just like IIS.

I had a similar error while saving several thousand participants to a database in PHP. Because in general, with fewer queries, the above script works. So I think their amount is killing him.

In my case of the attendee import script, using the transaction was enough to fix the problem.

2021-05-21_11h49_13.png (6,395 bytes)   

2021-05-21_11h49_13.png (6,395 bytes)   

Can you share some of the code you tested? You can do a pull-request too, if you want.

I don't understand. Why would there be too many queries?
Do you maybe get a timeout on the server?

There is no such thing of too many queries. The server does not care about the number of queries, as they are all sequential.

There are only two scenarios that could cause this:
Either running out of memory (less like) or out of time. The reason for the error should be visible in your webserver logs.

In general don't think that it is a LimeSurvey problem but a server configuration problem.

I will come back to this topic when I have more free time, I will describe the problem in more detail.

In fact, token generation can be a matter of server configuration.

But moving participants from the Central Base to the survey or from the survey to the Central Base. If there are, for example, 20,000, you have to be patient, because when sending more than 2,000 records, an error 500 will appear every time.

It sounds to me a like a timeout problem.
You should try to increase max_execution_time in your PHP configuration and in your webserver settings (the exact setting depends on the webserver software you are using)
That will most likely fix the problem.
I will close this issue now as it is not an original problem of LimeSurvey but of resources.
Thank you for your understanding.