description.short 80-character limit not documented for additionalLanguages localization files — causes silent CreateUserAppDefinitionFailed on Teams UI sideload

Question

description.short 80-character limit not documented for additionalLanguages localization files — causes silent CreateUserAppDefinitionFailed on Teams UI sideload

Yogesh Prajapati 0 Microsoft External Staff

Affected docs

https://learn.microsoft.com/en-us/microsoft-365/extensibility/schema/loc-schema/root?view=m365-app-1.29&tabs=syntax&source=docs

Summary

The description.short property has a hard maximum length of 80 characters that is enforced by the Teams Settings Store (definitionv2 endpoint) on every localization file referenced via localizationInfo.additionalLanguages, not just the root manifest. When any localized description.short exceeds 80 characters, Teams UI sideload fails with a generic CreateUserAppDefinitionFailed / Schema validation errors error that gives the developer no indication of which field or which locale file caused the failure.

This is documented inconsistently and incompletely in this page.

Ashlesha Pawar (Tata Consultancy Services Limited) 335 Reputation points Microsoft External Staff

2026-06-22T11:46:26.7466667+00:00

Hi Yogesh,

Thank you for the detailed report. We agree this is a valid documentation gap — the 80-character limit for description.short is referenced in the root description schema but is not explicitly documented in the localization schema reference page you linked. We are escalating this internally to the Microsoft Teams extensibility documentation team for review and correction. We will update this thread once we have confirmation on the doc update timeline.

In the meantime, please ensure all description.short values across every locale file in additionalLanguages are kept within 80 characters as a workaround.
Ashlesha Pawar (Tata Consultancy Services Limited) 335 Reputation points Microsoft External Staff

2026-06-29T11:50:40.67+00:00
Thanks for the detailed report. After checking with the team, the 80-character limit for description.short is already defined in the official Teams localization JSON schemas across all supported manifest versions:

https://developer.microsoft.com/json-schemas/teams/v1.29/MicrosoftTeams.Localization.schema.json

The JSON schema files serve as the authoritative reference for field constraints. The limit may not be explicitly repeated on every human-readable doc page, but it is enforced consistently across all localization files in additionalLanguages.

Workaround: Keep all description.short values in every locale file within 80 characters to avoid the silent CreateUserAppDefinitionFailed error.
Yogesh Prajapati 0 Reputation points Microsoft External Staff

2026-06-30T11:37:02.59+00:00

Hi @Ashlesha Pawar (Tata Consultancy Services Limited) ,
The constraint column for the description.short property is visible, but it is empty, which points to a real documentation gap.

1 answer

Your answer

Ashlesha Pawar (Tata Consultancy Services Limited) 335 Reputation points Microsoft External Staff

2026-06-22T11:46:26.7466667+00:00

Hi Yogesh,

Thank you for the detailed report. We agree this is a valid documentation gap — the 80-character limit for description.short is referenced in the root description schema but is not explicitly documented in the localization schema reference page you linked. We are escalating this internally to the Microsoft Teams extensibility documentation team for review and correction. We will update this thread once we have confirmation on the doc update timeline.

In the meantime, please ensure all description.short values across every locale file in additionalLanguages are kept within 80 characters as a workaround.
Ashlesha Pawar (Tata Consultancy Services Limited) 335 Reputation points Microsoft External Staff

2026-06-29T11:50:40.67+00:00

Thanks for the detailed report. After checking with the team, the 80-character limit for description.short is already defined in the official Teams localization JSON schemas across all supported manifest versions:

https://developer.microsoft.com/json-schemas/teams/v1.29/MicrosoftTeams.Localization.schema.json

The JSON schema files serve as the authoritative reference for field constraints. The limit may not be explicitly repeated on every human-readable doc page, but it is enforced consistently across all localization files in additionalLanguages.

Workaround: Keep all description.short values in every locale file within 80 characters to avoid the silent CreateUserAppDefinitionFailed error.
Yogesh Prajapati 0 Reputation points Microsoft External Staff

2026-06-30T11:37:02.59+00:00

Hi @Ashlesha Pawar (Tata Consultancy Services Limited) ,
The constraint column for the description.short property is visible, but it is empty, which points to a real documentation gap.

Answer 1

Hi Yogesh Prajapati

Thank you for sharing this information.

Based on my understanding, the documentation you referenced does not appear to provide complete alignment with what is described elsewhere, where an 80-character limit is mentioned.

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For your reference, you may review: root.description object | Microsoft Learn

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