Exception in opening add lightbox

Hi pressing the first “+” in bold gives

with 6.1.1 (evaluation version)

Hi @trony2014 !

We’re not aware of such problem in v6.1.1, and so far I was unable to reproduce it.
I’ve checked a couple of our demos, e.g. https://docs.dhtmlx.com/gantt/samples/01_initialization/01_basic_init.html
and https://docs.dhtmlx.com/gantt/samples/11_resources/10_resource_histogram_workload_percents.html
I pressed “+” button and it worked as expected.
So the issue may be caused by the configuration of your gantt, and I won’t be able to reproduce it with some further info.
Can you please share the code you configure gantt with.
If possible, please, add the required code and configuration to this snippet and reproduce the issue there
Then click on the “share” button and send me the link.