# What is “requiresReadingCheckpoint()” or “requiresWritingCheckpoint()”?

**URL:** <https://precice.discourse.group/t/what-is-requiresreadingcheckpoint-or-requireswritingcheckpoint/2698>\
**Category:** Using preCICE\
**Tags:** openfoam, calculix, fsi\
**Created:** [January 2, 2026, 6:24am UTC](https://precice.discourse.group/t/what-is-requiresreadingcheckpoint-or-requireswritingcheckpoint/2698 "2026-01-02T06:24:23Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![HHao-gihub](https://yyz2.discourse-cdn.com/free1/user_avatar/precice.discourse.group/hhao-gihub/32/2930_2.png) [@HHao-gihub](https://precice.discourse.group/u/HHao-gihub)\
**Post date:** [January 2, 2026, 6:24am UTC](https://precice.discourse.group/t/what-is-requiresreadingcheckpoint-or-requireswritingcheckpoint/2698/1 "2026-01-02T06:24:23Z")

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I created a test case myself without modifying any code, yet encountered the following error: —[precise] ERROR: The required operation `write-iteration-checkpoint` is not satisfied. Did you forget to call `requiresReadingCheckpoint()` or `requiresWritingCheckpoint()`?

How should I go about solving this problem?

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**Author:** ![ajaust](https://yyz2.discourse-cdn.com/free1/user_avatar/precice.discourse.group/ajaust/32/160_2.png) [@ajaust](https://precice.discourse.group/u/ajaust)\
**Post date:** [January 4, 2026, 4:11pm UTC](https://precice.discourse.group/t/what-is-requiresreadingcheckpoint-or-requireswritingcheckpoint/2698/2 "2026-01-04T16:11:06Z")

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Could you share the code and the coupling configuration that leads to this error?

My guess would be that you use an implicit coupling and in this case preCICE expects you to check whether a checkpoints must be read or written, see the [Implicit Coupling section in the docs](https://precice.org/couple-your-code-implicit-coupling.html).

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**Author:** ![HHao-gihub](https://yyz2.discourse-cdn.com/free1/user_avatar/precice.discourse.group/hhao-gihub/32/2930_2.png) [@HHao-gihub](https://precice.discourse.group/u/HHao-gihub)\
**Post date:** [January 6, 2026, 6:19am UTC](https://precice.discourse.group/t/what-is-requiresreadingcheckpoint-or-requireswritingcheckpoint/2698/3 "2026-01-06T06:19:11Z")

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Thank you for your response. The issue is that the time step should not exceed the maximum time step set in the XML file.

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**Author:** ![ajaust](https://yyz2.discourse-cdn.com/free1/user_avatar/precice.discourse.group/ajaust/32/160_2.png) [@ajaust](https://precice.discourse.group/u/ajaust)\
**Post date:** [January 6, 2026, 8:26pm UTC](https://precice.discourse.group/t/what-is-requiresreadingcheckpoint-or-requireswritingcheckpoint/2698/4 "2026-01-06T20:26:32Z")

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Great that you could figure it out. 🙂

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**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/precice/original/1X/67d2a5fa6f80e597e2267ff17fa8c1673cd11caa.svg) [@system](https://precice.discourse.group/u/system)\
**Post date:** [January 9, 2026, 8:26pm UTC](https://precice.discourse.group/t/what-is-requiresreadingcheckpoint-or-requireswritingcheckpoint/2698/5 "2026-01-09T20:26:38Z")

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