# Writing tag value inside a SFC Action step

**URL:** <https://forum.inductiveautomation.com/t/writing-tag-value-inside-a-sfc-action-step/32833>\
**Category:** Ignition\
**Created:** [March 5, 2020, 2:13pm UTC](https://forum.inductiveautomation.com/t/writing-tag-value-inside-a-sfc-action-step/32833 "2020-03-05T14:13:42Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![twstevic](https://avatars.discourse-cdn.com/v4/letter/t/a183cd/32.png) [@twstevic](https://forum.inductiveautomation.com/u/twstevic)\
**Post date:** [March 5, 2020, 2:13pm UTC](https://forum.inductiveautomation.com/t/writing-tag-value-inside-a-sfc-action-step/32833/1 "2020-03-05T14:13:42Z")

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Using Ignition 8.0.7

In the SFC editor, when attempting to write a value to a string tag using ‘system.tag.writeBlocking’, I get the error :  
Cannot coerce value ‘[default]SFC\_String’ into type: interface java.util.List

If I use ‘system.tag.write’, everything works. Isn’t this function deprecated?

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<div class="post-metadata">

**Author:** ![JordanCClark](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/jordancclark/32/83362_2.png) [@JordanCClark](https://forum.inductiveautomation.com/u/JordanCClark)\
**Post date:** [March 5, 2020, 2:15pm UTC](https://forum.inductiveautomation.com/t/writing-tag-value-inside-a-sfc-action-step/32833/2 "2020-03-05T14:15:58Z")

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writeBlocking uses lists of tags and values, like the old writeAll function.

```python
system.tag.writeBlocking(['[default]SFC_String'], ['your_value_here'])

```

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<div class="post-metadata">

**Author:** ![twstevic](https://avatars.discourse-cdn.com/v4/letter/t/a183cd/32.png) [@twstevic](https://forum.inductiveautomation.com/u/twstevic)\
**Post date:** [March 5, 2020, 2:42pm UTC](https://forum.inductiveautomation.com/t/writing-tag-value-inside-a-sfc-action-step/32833/3 "2020-03-05T14:42:27Z")

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Yes, indeed it does. I missed the list part in the documentation. Thank you.