# Precice error message: data is not marked as read

**URL:** <https://precice.discourse.group/t/precice-error-message-data-is-not-marked-as-read/205>\
**Category:** Using preCICE\
**Created:** [April 13, 2020, 2:15pm UTC](https://precice.discourse.group/t/precice-error-message-data-is-not-marked-as-read/205 "2020-04-13T14:15:40Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Claudio](https://avatars.discourse-cdn.com/v4/letter/c/7cd45c/32.png) [@Claudio](https://precice.discourse.group/u/Claudio)\
**Post date:** [April 13, 2020, 2:15pm UTC](https://precice.discourse.group/t/precice-error-message-data-is-not-marked-as-read/205/1 "2020-04-13T14:15:40Z")

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Hi,  
I am writing a dummy structural adapter to couple with A fluid solver for testing. I have done the other way round (a dummy fluid solver) and anything works. Now, when I initialize the interface and write:

```
   if self.interface.is_action_required(precice.action_write_initial_data()):
       self.interface.write_block_vector_data(self.displacementID, self.nodeVertexIDs, self.displacement)
       self.interface.mark_action_fulfilled(precice.action_write_initial_data())
   self.interface.initialize_data()
   if self.interface.is_read_data_available():
       self.force = self.interface.read_block_vector_data(self.forceID, self.nodeVertexIDs)

```

It enters in “is\_read\_data\_available” but gives me the following error:

—[precice] initializeData is skipped since no data has to be initialized  
—[precice] ERROR: Data is not marked as read! 3

What’s happening?  
Thank you  
Claudio

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<div class="post-metadata">

**Author:** ![uekerman](https://yyz2.discourse-cdn.com/free1/user_avatar/precice.discourse.group/uekerman/32/2199_2.png) [@uekerman](https://precice.discourse.group/u/uekerman)\
**Post date:** [April 14, 2020, 6:36am UTC](https://precice.discourse.group/t/precice-error-message-data-is-not-marked-as-read/205/2 "2020-04-14T06:36:55Z")

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Hi Claudio,

You are trying to read a data field that in the preCICE configuration is listed as “write” for this participant. In your case, `self.forceID` is not a data field that the dummy structure solver reads. Please check your config file and your `getDataID`.

Please note that `is_read_data_available` can still be true. You are simply accessing the wrong data.

The error message could be better. We are working on improving error messages including this one: [https://github.com/precice/precice/issues/680](https://github.com/precice/precice/issues/680) and [https://github.com/precice/precice/issues/698](https://github.com/precice/precice/issues/698).

Benjamin

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<div class="post-metadata">

**Author:** ![Claudio](https://avatars.discourse-cdn.com/v4/letter/c/7cd45c/32.png) [@Claudio](https://precice.discourse.group/u/Claudio)\
**Post date:** [April 14, 2020, 9:24am UTC](https://precice.discourse.group/t/precice-error-message-data-is-not-marked-as-read/205/3 "2020-04-14T09:24:52Z")

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Hi Benjamin,  
thank you for your answer. It solved my problem. I was pointing to the wrong data.  
Claudio