# XMLRPC Error - "Unknown Error: ValueStack is Full, capacity = 2048, needed Size = 2052"

**URL:** <https://forum.universal-robots.com/t/xmlrpc-error-unknown-error-valuestack-is-full-capacity-2048-needed-size-2052/6845>\
**Category:** URCap Development\
**Tags:** xml-rpc\
**Created:** [March 31, 2020, 8:57pm UTC](https://forum.universal-robots.com/t/xmlrpc-error-unknown-error-valuestack-is-full-capacity-2048-needed-size-2052/6845 "2020-03-31T20:57:17Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![terryc](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.universal-robots.com/terryc/32/3006_2.png) [@terryc](https://forum.universal-robots.com/u/terryc)\
**Post date:** [March 31, 2020, 8:57pm UTC](https://forum.universal-robots.com/t/xmlrpc-error-unknown-error-valuestack-is-full-capacity-2048-needed-size-2052/6845/1 "2020-03-31T20:57:17Z")

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Hey folks,

Has anyone encountered this error before?

[Google photos link to error message](https://photos.app.goo.gl/rd7gPj8iL1zxik697)

It only showed up when trying to send an array of length 3001 over xmlrpc on a 5.6 UR3e.

It does work fine in the following conditions:

- Robot software 5.5 and below. (tested on a 5.5 machine, 5.4.2 machine, 5.5 ursim and 3 ursim)
- when sending arrays smaller than 512 elements.(tested by setting up python 2.7 server on machine in question)

I also notice that there was some work done to XMLRPC as of **RELEASE NOTES 5.6.0 - 05/12-2019**

“Fixed an issue where XML-RPC call could result in controller crash”

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<div class="post-metadata">

**Author:** ![terryc](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.universal-robots.com/terryc/32/3006_2.png) [@terryc](https://forum.universal-robots.com/u/terryc)\
**Post date:** [March 28, 2021, 2:43am UTC](https://forum.universal-robots.com/t/xmlrpc-error-unknown-error-valuestack-is-full-capacity-2048-needed-size-2052/6845/2 "2021-03-28T02:43:05Z")

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Just wanted to update this in case anyone else runs across the same issue. Here is the latest response from UR support on the matter:

> “The only immediate action that the UR team will be performing is to improve the documentation to be more clear on the array limit of XMLRPC. There is currently not a big enough business case to justify making this update as I have been told that this change would be intensive to apply.”

We’ve implemented the same functionality with sockets, and I would recommend anyone else do the same for network transfer of large arrays.