Hello,
Sorry if i bring up a somewhat old conversation.
I would just like to say that i have the same problem as @Joseph_Namey.
i have tried to mirror the code in the documentation but i still get the error:
blazor.server.js:15 [2020-04-27T18:00:45.478Z] Error: System.InvalidOperationException: Collection was modified; enumeration operation may not execute.
at System.Collections.Generic.List`1.Enumerator.MoveNext()
at System.Linq.Enumerable.CastIterator[TResult](IEnumerable source)+MoveNext()
at System.Collections.Generic.List`1.InsertRange(Int32 index, IEnumerable`1 collection)
at System.Dynamic.UpdateDelegates.UpdateAndExecuteVoid2[T0,T1](CallSite site, T0 arg0, T1 arg1)
at Radzen.DropDownBase`1.SelectItemFromValue(Object value)
at Radzen.DropDownBase`1.OnParametersSetAsync()
at Microsoft.AspNetCore.Components.ComponentBase.CallOnParametersSetAsync()
at Microsoft.AspNetCore.Components.ComponentBase.SetParametersAsync(ParameterView parameters)
at Radzen.DataBoundFormComponent`1.SetParametersAsync(ParameterView parameters)
at Microsoft.AspNetCore.Components.Rendering.ComponentState.SetDirectParameters(ParameterView parameters)
at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.UpdateRetainedChildComponent(DiffContext& diffContext, Int32 oldComponentIndex, Int32 newComponentIndex)
at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.AppendDiffEntriesForFramesWithSameSequence(DiffContext& diffContext, Int32 oldFrameIndex, Int32 newFrameIndex)
at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.AppendDiffEntriesForRange(DiffContext& diffContext, Int32 oldStartIndex, Int32 oldEndIndexExcl, Int32 newStartIndex, Int32 newEndIndexExcl)
at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.AppendDiffEntriesForFramesWithSameSequence(DiffContext& diffContext, Int32 oldFrameIndex, Int32 newFrameIndex)
at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.AppendDiffEntriesForRange(DiffContext& diffContext, Int32 oldStartIndex, Int32 oldEndIndexExcl, Int32 newStartIndex, Int32 newEndIndexExcl)
at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.AppendDiffEntriesForFramesWithSameSequence(DiffContext& diffContext, Int32 oldFrameIndex, Int32 newFrameIndex)
at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.AppendDiffEntriesForRange(DiffContext& diffContext, Int32 oldStartIndex, Int32 oldEndIndexExcl, Int32 newStartIndex, Int32 newEndIndexExcl)
at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.AppendDiffEntriesForFramesWithSameSequence(DiffContext& diffContext, Int32 oldFrameIndex, Int32 newFrameIndex)
at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.AppendDiffEntriesForRange(DiffContext& diffContext, Int32 oldStartIndex, Int32 oldEndIndexExcl, Int32 newStartIndex, Int32 newEndIndexExcl)
at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.ComputeDiff(Renderer renderer, RenderBatchBuilder batchBuilder, Int32 componentId, ArrayRange`1 oldTree, ArrayRange`1 newTree)
at Microsoft.AspNetCore.Components.Rendering.ComponentState.RenderIntoBatch(RenderBatchBuilder batchBuilder, RenderFragment renderFragment)
at Microsoft.AspNetCore.Components.RenderTree.Renderer.RenderInExistingBatch(RenderQueueEntry renderQueueEntry)
at Microsoft.AspNetCore.Components.RenderTree.Renderer.ProcessRenderQueue()
Can anyone please help me out? This error happens as soon that i try to click one of the options i have defined.