Here is more on the error:
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Sonarr.Http.REST.BadRequestException: BadRequest: file must be provided at Sonarr.Api.V3.System.Backup.BackupModule.UploadAndRestore () [0x000ae] in M:\BuildAgent\work\63739567f01dbcc2\src\Sonarr.Api.V3\System\Backup\BackupModule.cs:110 at Sonarr.Api.V3.System.Backup.BackupModule.<.ctor>b__4_1 (System.Object x) [0x00000] in M:\BuildAgent\work\63739567f01dbcc2\src\Sonarr.Api.V3\System\Backup\BackupModule.cs:34 at Nancy.NancyModule+<>c__DisplayClass38_01[T].<Post>b__0 (System.Object args) [0x00047] in <e31b230dbd29407fadcc55713e0bbd0f>:0 at Nancy.NancyModule+<>c__DisplayClass40_0
1[T].b__0 (System.Object args, System.Threading.CancellationToken ct) [0x00047] in :0 at Nancy.Routing.Route`1[T].Invoke (Nancy.DynamicDictionary parameters, System.Threading.CancellationToken cancellationToken) [0x00017] in :0 at Nancy.Routing.DefaultRouteInvoker.Invoke (Nancy.Routing.Route route, System.Threading.CancellationToken cancellationToken, Nancy.DynamicDictionary parameters, Nancy.NancyContext context) [0x00086] in :0 at Nancy.Routing.DefaultRequestDispatcher.Dispatch (Nancy.NancyContext context, System.Threading.CancellationToken cancellationToken) [0x002b7] in :0 at Nancy.NancyEngine.InvokeRequestLifeCycle (Nancy.NancyContext context, System.Threading.CancellationToken cancellationToken, Nancy.Bootstrapper.IPipelines pipelines) [0x0011d] in :0
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