Please help us help you and fill where relevant:
LimeSurvey version: LimeSurvey Community Edition Version 6.16.3+251215
Own server or LimeSurvey Cloud: Own
Survey theme/template: Not relevant
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I see:

500: Internal Server Error - Alias "application.controllers.admin.Update" is invalid. Make sure it points to an existing PHP file and the file is readable.

after wanting to update on my Limesurvey installation that I have just moved from one server to another, while also changing the URL. Do you know what is the matter here?

I checked: the file update.php is present in the folder application/controllers/admin
But it is spelled as update.php and not Update.php.

Thanks in advance,

Tammo

And no improvement after clearing the LimeSurvey cache and the browser cache.