new theme gives blank page

Here is a tutorial on installing WordPress in a subfolder: https://www.wpbeginner.com/wp-tutorials/how-to-install-wordpress-in-a-subdirectory-step-by-step/

After you first installed WordPress, did it appear to work with the default theme?

Thanks Keith,

The default theme (2017) worked well after installation and setup. Problems started after trying to change the theme. No 404 error, but a totaly blank page page. No interface or way to go back exept for the reverse button of the browser.
Trying several theme’s gave the same bug.

kindly, Alice

How are you changing the theme? Are you uploading a theme you downloaded, or are you browsing the themes via the dashboard?

Still working on it, isn’t fixed yet.
I uplaoded the theme via the dashboard and looks like that went well, but maybe not because activating the theme still gives a blank page.
Is it better to uplaod the theme by FTP?
By the way, I build the website with this theme with Xamp on my laptop.

below is the error path;
https://www.dansdrift.nl/ddcms/wp-admin/customize.php?theme=agama-blue&changeset_uuid=6be2dabb-6cce-4387-9131-1d4f6e13bd4e&return=http%3A%2F%2Fwww.dansdrift.nl%2Fddcms%2Fwp-admin%2F

Problem solved. Thanks for help.

kind regards, Alice