in put i  tried $edit and $create but i got same response.

Hi,

You can check this post with detailed instructions, just to see if you missed any step:
https://www.sagecity.com/support_communities/sage_erp_x3/b/sageerp_x3_product_support_blog/posts/how-to-use-rest-web-services-to-get-and-post-a-record

Also, check that the Creation and Modification checkboxes are active on the Class.

Regards,

Alex

yea everything is correct i didn't miss any but still can't update or create.

i am afraid that even in v12 we still can't edit some objects using REST API.

Maybe then you could try to duplicate class and representation, instead of modifying out-of-the-box ones.

maybe it's good idea i am new to sage x3, so i will try it and return with result

Thankyou so much for your help.

Posting via REST on duplication worked for BPADDRESS and BPARTNER but not for ITMMASTER and BPCUSTOMER maybe it's problem of foreign keys or something. but thank you for this idea :)