I hope that here is the right place to insert this issue.
It has been annoying, and a disappointment to the respondents of my surveys, to receive the "Session expired" message (please see attachments), after being focused and committed to the survey filling. This is worst when they are responding to exams.
I have the 4.2.8+200608 version installed.
I wonder if I have something wrongly configured and/or this is an issue regarding cookie's configuration of the respondents web browser.
This is generally a problem of your server settings, which are usually responsible for a session timing out. Have a look at the PHP sessions on your server regarding this.
However, if someone is really dedicated to the survey, even a relatively low session life time shouldn't be a problem, only if you stop moving within the survey for a longer period of time.
Of course, this can happen if you have many questions on the same page so it takes a long time for them to move to the next page, or if you have text questions where long answers are required.
In any way, and this has nothing to do with the session problem, I currently would not recommend to use LS 4.x for any production use. My recommendation would be to use 3.x. for the moment.
Help us to help you!
Provide your LS version and where it is installed (own server, uni/employer, SaaS hosting, etc.).
Always provide a LSS file (not LSQ or LSG).
Note: I answer at this forum in my spare time, I'm not a LimeSurvey GmbH employee.
These are other values that might be also interesting. Max_execution_time for example could cause problems when you have very big surveys and when you export the data, you might run into trouble. But generally 30 seconds is enough for normal use. I would only change this, if there is a problem one day with a script timing out.