Update error on checklist field, Field validation failure

[ITI]

I think this originated in a (very) old version.
Because when I now test with and without spaces, everything works fine with newly created fields....

[ITI]

When you asked me i look into that file found this

"algemeneLedenvergadering": {
"type": "checklist",...

[ITI]

I have done all above, including hard rebuild. Unfortunally no succes.
I have delete all the fields with stange chars, so I have only a-z.
...

[ITI]

I ve upload new images, one with settings (that is complete, before i made 2 screenshots)

[ITI]

I ve upload it to the first post

[ITI]

Hello, we update Espo from version 5 till 9, everything works fine but we have one issue.
An checklist filed give the error in /data/log >>...