"There was an error processing the manifest file"

Make sure you don't have any preview device in the manifest

I also had this problem，There are no preview devices in my manifest，How to solve this problem?

<?xml version="1.0" encoding="UTF-8"?>
<iq:manifest version="3" xmlns:iq="http://www.garmin.com/xml/connectiq">
    <iq:application 
        entry="FiveElementWatchFaceApp" 
        id="53D5641D86C04C5CAD2941544934DED8" 
        launcherIcon="@Drawables.LauncherIcon" 
        minSdkVersion="4.2.0" 
        name="@Strings.AppName" 
        type="watchface" 
        version="1.0.0">
        
        <iq:products>
            <iq:product id="fr965"/>
            <iq:product id="fr255"/>
            <iq:product id="fr265"/>
            <iq:product id="fr265s"/>
            <iq:product id="venu3"/>
            <iq:product id="venu3s"/>
        </iq:products>
        
        <iq:permissions>
            <iq:uses-permission id="UserProfile"/>
        </iq:permissions>
        
        <iq:languages>
            <iq:language>eng</iq:language>
            <iq:language>zho</iq:language>
        </iq:languages>
        
        <iq:barrels/>
    </iq:application>
</iq:manifest>

Because it won't work and because the developer dashboard (probably intentionally?) doesn't give a meaningful error message. In some cases you might be able to see a more detailed error message by looking at some json in the developer console of your browser.