Maximum duration of task is one month

Why I can’t create task with duration more than 1 months? How I can set up this property???

Hello Tanya,
Unfortunately, I couldn’t reproduce that issue:
http://snippet.dhtmlx.com/e3e4eafdf
https://files.dhtmlx.com/30d/da81b1cfb6a977d1d0ea3306fa8d313c/vokoscreen-2019-11-25_14-23-21.avi

Probably, it is related to Gantt configuration, but it is hard to suggest what might be wrong as I don’t see your code. Please, reproduce the issue in the snippet, then click on the “Share” button and send me the link:
https://snippet.dhtmlx.com/38ee1b370
Or send me an HTML file with all the necessary Javascript and CSS files.

May be that’s because I set duration in minutes?

Hello Tanya,
I cannot reproduce the issue if I set the duration in minutes:
https://files.dhtmlx.com/30d/fd224871e1a138da2d8865d3a846ac78/vokoscreen-2019-12-05_11-10-27.avi
http://snippet.dhtmlx.com/b50cfcab7

If you don’t know how to reproduce the issue, apply the function from the following snippet in your application with Gantt:
http://snippet.dhtmlx.com/102481b0e
It will save the configuration and the data in a text file. You can replace the important data from the file and send it to me, and I will try to reproduce the issue by using your configuration.