[hh2]

What is the max size for datapack writing?

[asherkin]

About 4GiB - 4,294,967,295 bytes, but you'll run out of address space long before you reach it.

What makes you think it is only 4,000 bytes?

[hh2]

I created simple plugin to simulate writing string data to pack.
Limit for loop is 150 iterations.
After reading 106 strings each 32 chars max length, my console get spammed with this message:

SendNetMsg <IP address>: stream[netchan_t::unreliabledata] buffer overflow (maxsize = 4000)!

[asherkin]

You printed too much to the client console in a single frame, nothing to do with the datapack.

[hh2]

Ok, my fault.
Thanks for your help.