I am using powershell to upload a RDL file to a specific folder in a SSRS instance (SQL Server 2019 Reporting Services Version 15.0.8863.19101)

    $sourceItemPath = 'C:TempReportFolderReport.rdl'
    $reportName = 'Report'
    $apiPath = 'http://localhost/reports/api/v2.0'
    $creds = New-Object System.Management.Automation.PSCredential ($SSRSReportUser, $SecurePassword)
    $targetPath = "/Reports"
    $sourceFileContent = [System.IO.File]::ReadAllBytes($sourceItemPath)
    $sourceFileContent2 = [System.Convert]::ToBase64String( $sourceFileContent )

    # ------------------
    # Create Report
    # ------------------

    $CreateReportJSON=
    '
    {
        "@odata.type": "#Model.Report",
        "Content": "YYY",
        "ContentType": "application/rdl",
        "Name":  "XXX",
        "Path":  "/ZZZ/XXX"
    }
    '
    $targetPath = $targetPath.Replace('/','')
    $CreateReportJSON = $CreateReportJSON.Replace('XXX',$reportName)
    $CreateReportJSON = $CreateReportJSON.Replace('YYY',$sourceFileContent2)
    $CreateReportJSON = $CreateReportJSON.Replace('ZZZ',$targetPath)
    $CreateReportURI = "$apiPath/Reports(Path='/$targetPath')"
    $createReportResponse = Invoke-RestMethod -Uri $CreateReportURI -Method POST -ContentType 'application/json' -Body $CreateReportJSON -Credential $creds

When I attempt to upload the report, I get the following error.

Invoke-RestMethod : {
  "error":{
    "code":"1027","message":"The definition of this report is not valid or supported by this version of Reporting Services. The report definition may have been created with a later version of Reporting Services, or contain content that is not well-formed 
or not valid based on Reporting Services schemas. Details: Invalid character in the given encoding. Line 1206, position 80."
  }
}

The beginning of the file is…

<?xml version="1.0" encoding="utf-8"?>
<Report xmlns="http://schemas.microsoft.com/sqlserver/reporting/2016/01/reportdefinition" xmlns:rd="http://schemas.microsoft.com/SQLServer/reporting/reportdesigner" xmlns:am="http://schemas.microsoft.com/sqlserver/reporting/authoringmetadata">

I can upload the file via the SSRS UI! Why can’t I upload it via Powershell? Can I get rid of the schema validation?