XML Schema Validation Errors

Question

XML Schema Validation Errors

Arnav Garg 10

Hey! I'm trying to upload my manifest.xml package to the Microsoft Office Store for my Excel add-in, which has a CustomTab based ribbon for added user functionality. However, I get the following error: Package acceptance validation error: XML Schema Validation Error Error found during XML Schema validation. Error code: The element 'CustomTab' in namespace 'http://schemas.microsoft.com/office/taskpaneappversionoverrides' has invalid child element 'Label' in namespace 'http://schemas.microsoft.com/office/taskpaneappversionoverrides'. List of possible elements expected: 'Group, OfficeGroup' in namespace 'http://schemas.microsoft.com/office/taskpaneappversionoverrides'.

This is because there is a Label after my CustomTab tag opens, but without that Label, the Add-in ceases to sideload - is that normal? I've tried putting in a dummy placeholder group, but the sideloading still doesn't work, and I've also tried putting the Label in the first Group declared

Daniel G Brown 30 Reputation points

2024-11-23T02:40:13.0566667+00:00

I am getting this error when I use a CustomTab in my manifest for an Excel addin and validate the manifest. The addin does load and uses the Label as the Ribbon identifier. If I remove the Label, then the validate manifest fails because the Label is missing.

3 answers

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Daniel G Brown 30 Reputation points

2024-11-23T02:40:13.0566667+00:00

I am getting this error when I use a CustomTab in my manifest for an Excel addin and validate the manifest. The addin does load and uses the Label as the Ribbon identifier. If I remove the Label, then the validate manifest fails because the Label is missing.

Answer 1

Samuel Hartmann 0

I have the same error. I'm writing a Word add-in with a Custom Tab labelled "Math".

With the label and side-loading, everything worked.

The I wanted to upload the manifest to the integrated apps list, so that I can use my app without side-loading:

https://admin.microsoft.com/#/Settings/IntegratedApps

The upload failed.

The I checked using

npx office-addin-manifest validate .\manifest.xml

It failed due to the label directly under CustomTab.

Then I removed the label ➔ It failed CustomTab ... has incomplete content. List of possible elements expected: 'Group, OfficeGroup, Label'

I have my Groups there. So it expects the label. This seems to be a Microsoft bug.

I have no chance to upload my manifest with a CustomTab defined, since there will always be errors, without and with label. Do you know whether I will also fail upload to appsources?

Samuel Hartmann 0 Reputation points

2025-07-25T12:53:25.33+00:00

Finally, after some hours I found the solution. The validator said it was not happy with or without label. But the reason was the sequence: you have to put the Label tag at the end of the CustomTab tag after all Groups tags.

I learnt this from an example manifest containing CustomTab:

https://learn.microsoft.com/en-us/office/dev/add-ins/develop/xml-manifest-overview?tabs=tabid-1#version-overrides-in-the-manifest

Hope this helps you!

Samuel

Answer 2

Daniel Brown 0

I think I have gotten around this issue. Try putting the Label at the end of the Custom Tab section.

...

</Group>

...

</CustomTab>

Answer 3

Thanks, that helped!

What a pity that the validator is not telling this.

It also does not check wether some ids are dupplicated. May be also not non-existing resids.

Also, I cannot directly look at the schema (the browser does not load it):

http://schemas.microsoft.com/office/taskpaneappversionoverrides

But I found it by web search (or some version of it)

https://learn.microsoft.com/en-us/openspecs/office_file_formats/ms-owemxml/82e93ec5-de22-42a8-86e3-353c8336aa40

And here I can see:

<xs:complexType name="CustomTab">
     <xs:complexContent>
       <xs:extension base="Tab">
         <xs:sequence>
           <xs:choice minOccurs="1" maxOccurs="unbounded">
             <xs:element name="Group" type="Group"/>
             <xs:element name="OfficeGroup" type="OfficeGroup"/>
           </xs:choice>
           <xs:element name="Label" type="bt:ShortResourceReference" minOccurs="1" maxOccurs="1"/>
           <xs:choice minOccurs="0" maxOccurs="1">
             <xs:element name="InsertBefore" type="bt:ShortString"/>
             <xs:element name="InsertAfter" type="bt:ShortString"/>
           </xs:choice>
         </xs:sequence>
       </xs:extension>
     </xs:complexContent>
   </xs:complexType>

Probably sequence means:

First <Group> or <OfficeGroup>

Then <Label>

Then <InsertBefore> or <InsertAfter>

Any idea how, I can directly load and look at referenced schema files?

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XML Schema Validation Errors

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