# Error message: ndiagp is too small to read in STASHmaster

**URL:** <https://cms-helpdesk.ncas.ac.uk/t/error-message-ndiagp-is-too-small-to-read-in-stashmaster/2076>\
**Category:** Unified Model\
**Created:** [6 May 2026 08:29 UTC](https://cms-helpdesk.ncas.ac.uk/t/error-message-ndiagp-is-too-small-to-read-in-stashmaster/2076 "2026-05-06T08:29:11Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![mollymac](https://avatars.discourse-cdn.com/v4/letter/m/7ea924/32.png) [@mollymac](https://cms-helpdesk.ncas.ac.uk/u/mollymac)\
**Post date:** [6 May 2026 08:29 UTC](https://cms-helpdesk.ncas.ac.uk/t/error-message-ndiagp-is-too-small-to-read-in-stashmaster/2076/1 "2026-05-06T08:29:11Z")

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Hi,

I am getting the following error at atmos\_main running suite u-dz121:

 ![image](https://europe1.discourse-cdn.com/flex013/uploads/cms_support/original/1X/42652ee339186d232e621050b331b4d43fa7325a.jpeg)

It is a nudged suite running with the DEST chemistry scheme with a new branch to include iodine chemistry.

Would somebody be able to explain how to fix this?

Thank you,

Molly

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**Author:** ![mdalvi](https://avatars.discourse-cdn.com/v4/letter/m/ad7895/32.png) [@mdalvi](https://cms-helpdesk.ncas.ac.uk/u/mdalvi)\
**Post date:** [6 May 2026 08:50 UTC](https://cms-helpdesk.ncas.ac.uk/t/error-message-ndiagp-is-too-small-to-read-in-stashmaster/2076/2 "2026-05-06T08:50:41Z")

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Hi Molly,

_ndiagp_ is defined in [src/control/top\_level/version\_mod.F90](https://code.metoffice.gov.uk/trac/um/browser/main/trunk/src/control/top_level/version_mod.F90)[.](https://src/control/top_level/version_mod.F90) From the error message this seems to refer to the total number of fields/ diagnostics defined in STASHmaster. You can try bumping the value roughly by the number of new stash items added by your scheme, or randomly by a couple of hundreds first.

Mohit

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**Author:** ![system](https://europe1.discourse-cdn.com/flex013/uploads/cms_support/original/1X/1fd2411499ffcbc299fe756cd5cdf26e44956558.png) [@system](https://cms-helpdesk.ncas.ac.uk/u/system)\
**Post date:** [5 June 2026 08:51 UTC](https://cms-helpdesk.ncas.ac.uk/t/error-message-ndiagp-is-too-small-to-read-in-stashmaster/2076/3 "2026-06-05T08:51:06Z")

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