@ramadama wrote earlier:

i wanted test 'Specific post ID:' in Features/Front page and used a fictional ID 345 ( which is a post of another collection ). this setting did not work and i wanted change it back to another option, like 'Recent Posts' or 'Special Front page' ... but whatever i do, the Front page called, is the p=345 one and it shows a Fatal error as below.

'Whatever' you do means little and much, but not specific
A few things I would try.
a) Did you try a number of a real post? - result?
b) What happens if you try to set to 'Latest comment'
c) What exactly have you tried.
d) Are you happy to edit the database

And your redaction doesn't work
homepages/25/d30688299

a) Did you try a number of a real post? - result?

Created several real posts. They show the way they should. Front page still in trouble

b) What happens if you try to set to 'Latest comment'

no change. In back office the 'latest comment' radio button is checked, but the Front page still ends with p=345 once i use the http://activists365.wald.org/ address.

c) What exactly have you tried.

Don't know what you mean: either a) to end up in the problem or b) to solve the problem
If you refer to a) then it is choosen 'A specific page' with ID number 345 and if you refer to b), then it is more or less what you suggested: i tried different options of Front page settings and added some new posts, which behave well.

d) Are you happy to edit the database

if you have a good guess, where i would find the relevant detail, i could do. yes.

Thanks for your time spent on this!

Look at table [evo_coll_settings]
I haven't tried anything but the fields seem relevant [front_disp] and [font_post_ID]

Solved!

I tested last night switching all options for the Front page display and it did not change.
In the end I left it with the 'Users'-option and when i reloaded the site in the morning, it worked.

If I had more time, I would try to reproduce and check if the system gets stuck again as it did ... but can't do it the next three days.

thanks @amoun

Hopefully you have more enjoyable things to do that look for reproduce a problem even after three days :)