Thanks.

Would it be possible to find a definition of what a critical error means, please?

My understanding is that this relates to files that are offline, or not IATI XML - which are also listed, and updated daily, in the IATI dashboard:

http://dashboard.iatistandard.org/download.html
http://dashboard.iatistandard.org/xml.html

The IATI Registry also provides a list of the errors it encounters, some of which might be "critical" (when it can't find the data file, for example):

https://iatiregistry.org/report/issues (you need to be logged into the Registry to see this)

.. but it's be really helpful to understand exactly what is meant by this. Thanks

Where should we report mistakes by the Validator? (ie errors reported erroneously)

Hi both, the definition of critical errors is on the IATI Validator about page: https://iativalidator.iatistandard.org/about
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Check 1: Schema Validation- Critical

The IATI Validator checks if data adheres to the format set out in the IATI XML Schema. The IATI Schema provides the exact order and structure that organisations should provide their XML in. Full information about the IATI Schema can be found on IATI’s Reference site.
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As Steven Flower mentions, critically invalid includes all files that are not accessible, not in xml, don't follow the IATI element order or don't contain mandatory elements/attributes

Yohanna Loucheur for potential issues and bugs with the validator please let us know at support@iatistandard.org.