# Serialization error on custom property when saving project

**URL:** <https://forum.inductiveautomation.com/t/serialization-error-on-custom-property-when-saving-project/11849>\
**Category:** Ignition\
**Created:** [June 22, 2016, 8:27pm UTC](https://forum.inductiveautomation.com/t/serialization-error-on-custom-property-when-saving-project/11849 "2016-06-22T20:27:48Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Bob](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/bob/32/16899_2.png) [@Bob](https://forum.inductiveautomation.com/u/Bob)\
**Post date:** [June 22, 2016, 8:27pm UTC](https://forum.inductiveautomation.com/t/serialization-error-on-custom-property-when-saving-project/11849/1 "2016-06-22T20:27:48Z")

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Ignition 7.8.3  
Windows Server 2012

I have created a custom property of type Dataset with the following expression binding:

```auto
toDataSet(runScript("system.tag.browseTags(parentPath='Horizon OPC-UA Server/DeviceSet')"))
```

The expression appears to work fine because I get the exact results I was looking for.

I can save the project fine before adding this custom property, but I cannot save the project after I add the property.

I get this error below regarding a serialization error.

Any ideas what is causing this are appreciated.

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**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\
**Post date:** [June 22, 2016, 8:35pm UTC](https://forum.inductiveautomation.com/t/serialization-error-on-custom-property-when-saving-project/11849/2 "2016-06-22T20:35:09Z")

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For a dataset to be serializable, every element stored in it must also be serializable. Datasets can contain arbitrary object columns, but then will be unpredicatably saveable. You’ll need to rework your runScript to call out to a routine that interates through the result to pick out the values you really need, then use the system.dataset.toDataSet(headings, rows) form to get a saveable dataset.

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<div class="post-metadata">

**Author:** ![Bob](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/bob/32/16899_2.png) [@Bob](https://forum.inductiveautomation.com/u/Bob)\
**Post date:** [June 27, 2016, 5:32pm UTC](https://forum.inductiveautomation.com/t/serialization-error-on-custom-property-when-saving-project/11849/3 "2016-06-27T17:32:28Z")

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Thanks Phil!

I just got back to this and I’m all set with your help.