How can I increase the string size in AX? I want to increase the InventSerialId from 20 to Memo (unlimited), however, the field string size in this cannot be modified.
Hope you can get back to me.
Change the properties of the EDT(Extended data type).
No. You should not change this to a memo type.
The InventSerialId is a part of some indexes build on InventDim, InventSerial tables.
The Indexes should not contain field of type memo or container.
So rather changing the size of the InventSerialId make use of another field…
So Kranthi you are saying that fields that have string size colored as gray cannot really be modified at all?
Thanks Kranthi for that input. Now I know that I cannot increase the string size of InventSerialID
You can increase the length to an extent(by changing at EDT level) but it may effect your performance…
Yes that’s true. sometimes when I increase the string size, errors occur. 
Hi, i have also change string size in AX, from 60 to 160, but in form and table it didnt change, though on field properties it is correct size. How i can update it?
If the EDT has extends property on it, Go to the EDT extension mention on the “extends” property of the EDT and change the string size.
Ex: InventSerialId: if you want to change the its string size you can go the EDT mentioned on the 'extends" property of InventSerialId, there you can change its strings size.
Or if you want to change only the size of InventSerialId Alone try to delete the value on the ‘extends’ property, that way the Stringsize property of InventSerialId will be available for edit.
Hope this would help.
So, what i didt and worked, is i created new edt and changed field edt and it worked fine. Because than i change size of the same edt, it doesnt change anything.