the power pages management model driven app not working: empty pages

Hi,

this week my power pages management model driven application is displaying empty lists.

no more websites list displayed, no more lists, pages, page templates etc

all the lists are displaying an empty page instead of the standard grid with the content.

I see a huge amount of javascript errors using the browser's developer tools.

mainly "GetClientMetadata failed"

with these network calls:

fetch("<crm url>/api/data/v9.0/GetClientMetadata(ClientMetadataQuery=@ClientMetadataQuery)?@ClientMetadataQuery={%22MetadataType%22%3A%22savedview%22,%22MetadataSubtype%22%3A%22MAIN_APPLICATION_VIEW%22,%22EntityLogicalName%22%3A%22mspp_shortcut%22,%22GetDefault%22%3Atrue,%22DependencyDepth%22%3A%22OnDemandWithContext%22,%22ChangedAfter%22%3A%22410145434%22,%22AppId%22%3A%22b77e3f18-37ec-ed11-8849-000d3af4351b%22}&umv=410145434&mv=413475526&rde=1&api-version=9.1", {
"headers": {
"accept": "application/json",
"accept-language": "en,en-US;q=0.9,fr-CA;q=0.8,fr;q=0.7,en-CA;q=0.6,fr-FR;q=0.5",
"cache-control": "no-cache",
"clienthost": "Browser",
"content-type": "application/json",
"pragma": "no-cache",
"prefer": "odata.include-annotations=\"*\"",
"priority": "u=1, i",
"sec-fetch-dest": "empty",
"sec-fetch-mode": "cors",
"sec-fetch-site": "same-origin",
},
"referrer": "<crm url>/uclient/sw.js?cdn=true&gcm=true&uci=true&customPage=false&data=true&clientHost=1&cdnEndpoint=https://content.powerapps.com/resource/uci-infra-web/&cacheMain=true&cdnOwnCache=true",
"referrerPolicy": "strict-origin-when-cross-origin",
"body": null,
"method": "GET",
"mode": "cors",
"credentials": "include"
});

here the decoded payload:

@ClientMetadataQuery:

{"MetadataType":"savedview","MetadataSubtype":"MAIN_APPLICATION_VIEW","EntityLogicalName":"mspp_shortcut","GetDefault":true,"DependencyDepth":"OnDemandWithContext","ChangedAfter":"410145434","AppId":"b77e3f18-37ec-ed11-8849-000d3af4351b"}

here the response from the network call:

{

    "error": {

        "code": "0x80040216",

        "message": "GetClientMetadata failed",

        "@Microsoft.PowerApps.CDS.ErrorDetails.ApiExceptionSourceKey": "Plugin/Microsoft.Crm.Metadata.ClientMetadataService",

        "@Microsoft.PowerApps.CDS.ErrorDetails.ApiStepKey": "ccf82b1f-e835-4589-b782-8f6f5dbbcf76",

        "@Microsoft.PowerApps.CDS.ErrorDetails.ApiDepthKey": "1",

        "@Microsoft.PowerApps.CDS.ErrorDetails.ApiActivityIdKey": "71417d62-99e6-439b-9ce1-171aee34b192",

        "@Microsoft.PowerApps.CDS.ErrorDetails.ApiPluginSolutionNameKey": "System",

        "@Microsoft.PowerApps.CDS.ErrorDetails.ApiStepSolutionNameKey": "System",

        "@Microsoft.PowerApps.CDS.ErrorDetails.ApiExceptionCategory": "SystemFailure",

        "@Microsoft.PowerApps.CDS.ErrorDetails.ApiExceptionMessageName": "UnExpected",

        "@Microsoft.PowerApps.CDS.ErrorDetails.ApiExceptionHttpStatusCode": "500",

        "@Microsoft.PowerApps.CDS.HelpLink": "http://go.microsoft.com/fwlink/?LinkID=398563&error=Microsoft.Crm.CrmException%3a80040216&client=platform",

        "@Microsoft.PowerApps.CDS.InnerError.Message": "GetClientMetadata failed"

    }

}