Werk #22808: Forms: no crash on file upload fields

Component

Setup

Title

Forms: no crash on file upload fields

Date

Oct 19, 2026

Level

Trivial Change

Class

Bug Fix

Compatibility

Compatible - no manual interaction needed

Checkmk versions & editions

3.0.0b1 Not yet released	Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT
2.5.0p18 Not yet released	Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT
2.4.0p39	Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT

Saving or validating settings that contain a file upload field in a form of the older type (for example certificate or key uploads in notification parameters or in the agent updater rule) could fail with a crash report showing TypeError: Only str and unicode values are allowed. This also affected the REST API endpoints for configuration entities.

The form no longer crashes. Uploading a file is still not possible in these forms, though: if an upload field is selected, required or optional, the form now reports that file uploads are not supported here. Where the field offers it, paste the content instead.

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