Acumatica how to modify opportunity stageid Even if quote is accepted

The standard behavior is to disable modifications of some opportunity Fields when quote is not on hold. I don’t find in source code where is this rule and don’t know how to change this behavior.

Try this workflow extension, you may need to compile it into a DLL.

using PX.Data;
using PX.Data.WorkflowAPI;
using PX.Objects.CR;
using PX.Objects.CR.Workflows;

namespace Customization;

public class OpportunityWorkflowExt : 
    PXGraphExtension<OpportunityWorkflow, OpportunityMaint>
{
    public override void Configure(PXScreenConfiguration config)
    {
        var context = config.GetScreenConfigurationContext<OpportunityMaint, CROpportunity>();

        context.UpdateScreenConfigurationFor(screen =>
            screen
                .UpdateDefaultFlow(flows =>
                    flows.WithFlowStates(flowStates =>
                    {
                        flowStates.Update<OpportunityStatus.won>(state =>
                            state.WithFieldStates(fs =>
                                fs.AddField<CROpportunity.stageID>()));
                        flowStates.Update<OpportunityStatus.lost>(state =>
                            state.WithFieldStates(fs =>
                                fs.AddField<CROpportunity.stageID>()));
                    })));
    }
}