A proposed solution by « person responsible for the installation here.»
ALTER TABLE survey_123 ROW_FORMAT=DYNAMIC;

https://forums.limesurvey.org/index.php/forum/installation-a-update-issues/134834-limesurvey-version-5-cannot-activate-survey-too-many-questions?start=0

Maybe if we can add as default for mysql/InnoDB

Is this a future request?

If a feature request can get that problem solved/prioritized we gladly would like to sponsor it.

Seems like a simple backward-compatible fix.

The problem is still present and some of our customers are affected by it. The only solution we can come up with so far is to split a survey in multiple sub surveys, which is very annoying in an academic context ("survey has to start tomorrow").

Please find a better solution for it than a not very helpful error message after all the work is done and you just want to activate a survey. Maybe a fallback to MyISAM in that case?

Again, we would glady sponsor the development of a better solution. Thank you.

For InnoDB the ROW_FORMAT=DYNAMIC; does not make any difference regarding number of columns in the response table.
I don't see any solution here, at least for InnoDB. We are currently working on a solution that will raise number of maximum columns for MyISAM tables considerably, but there is no ETA, yet.

For InnoDB the ROW_FORMAT=DYNAMIC; does not make any difference regarding number of columns in the response table.

Yes, but the alert is ALWAYS too may question if you don't activate debug mode

See the working solution : https://forums.limesurvey.org/index.php/forum/installation-a-update-issues/134834-limesurvey-version-5-cannot-activate-survey-too-many-questions?start=0

(I have to report issue about this misleading alert…)

What about a fallback to MyISAM in case InnoDB reach its limits? Afaik LimeSurvey can handle a mixture of InnoDB/MyISAM tables just fine. Just don't let LimeSurvey pick the configurations Default-Engine everytime a survey is activated?