We are also getting this error.

In my case, the custom field contexts for Flagged were automatically created by Project Configurator, an add-on we use for projects imports from other Jira instances.  Each of these contexts looked just like the global context, that is, the only value was "Impediment".  I confirmed all projects with the custom context exhibited the error.  The fix was simple:  I just deleted the project-specific context, and the project then used the global context.  This fix would not have been as easy if the custom contexts had other values defined.  In that case, I would recommend the following:

For each project:

• create a new Checkboxes field with the same values and give it a descriptive name

• do a bulk move from Flagged to the new custom field (ensure no loss of data)
• do a bulk move to clear all the values in Flagged

• remove the Flagged custom field context for the project

I'd follow this up with some user insight into how to effectively use the Flagged field.  In my experience, teams use it flag issues that need discussion, even when there is no impediment.  Because these issues are shown in yellow with a flag indicator on the board, they definitely get attention.

Hope this helps someone on your Jira admin journey!

We've managed to resolve this in a test environment. If you are hitting this bug it is most likely due to the "Flagged" custom field having additional unnecessary contexts. The root / default context for Flagged should already be global and contain the single option expected ('Impediment' in English, 'Hindernis' in German, etc) so adding additional contexts is not necessary. I would NOT recommend trying to reuse the "Flagged" field as a regular Checkbox field! We got this bug after a migration which is how the additional contexts were created.

Using the Agile Board "Add Flag" function always applies optionID value 10000 for field Flagged which is why things break when you add additional contexts. Agile Boards are trying to set Flagged to optionID value 10000 and your additional context has set "Impediment" to another optionID value for this project/context.

Here's what we did in testing: 

• make a JQL that is roughly: "project in (all projects using the additional contexts) and Flagged is not EMPTY"
• add the Flagged column to the result and export results to CSV for safe keeping (make sure to set the values in the CSV to be what the system expects for the language its using – if you've migrated in another language there's a good chance their context/values will be in another language)
• we took snapshots of the additional contexts in case there were complications
• remove the additional contexts (WARNING: this will remove the data from the additional contexts using the Flagged field)
• using a CSV import, reapply the Flagged values using the External System Import tool

Hundereds of users are still suffering. We cannot flag our story. This is sad and bad. Please help us!

Same issue in our project:
"Ungültiger Wert '21153' für das benutzerdefinierte Feld 'Flagged' weitergegeben. Erlaubte Werte: 506017[Hindernis], -1"

Please fix it soon!

Hello ,
the problem also appeared in version  Jira v8.20.10

I agree that Flagged should be created as a Locked custom field by Jira Software. Not sure why it is not.

Our team is seeing this as well. Receiving the error "Invalid value "27334" passed for customfield 'Flags'. Allowed values are: 73000[Yes], -1"