Module '"@microsoft/sp-property-pane"' has no exported member 'PropertyPaneDatePicker'.

 The @microsoft/sp-property-pane package does not provide a PropertyPaneDatePicker control. If you're looking to add a date picker in the property pane of an SPFx web part, you can use the PropertyPaneCustomField control and integrate a third-party date picker component.

Here's an example of how you can use the PropertyPaneCustomField to add a date picker using the office-ui-fabric-react library:

1. Install the required packages:

bash
npm install office-ui-fabric-react

2. Import the necessary modules in your web part's TypeScript file:

typescript
import * as React from 'react';
import * as ReactDom from 'react-dom';
import { PropertyPaneCustomField } from '@microsoft/sp-property-pane';
import { DatePicker } from 'office-ui-fabric-react/lib/DatePicker';
import { IDatePickerProps } from 'office-ui-fabric-react/lib/DatePicker';

3. Create a custom property pane field component for the date picker:

typescript
export class DatePickerField implements IPropertyPaneField<any> {
  private elem: HTMLElement;
  private properties: any;
  private targetProperty: string;
  private onPropertyChange: (propertyPath: string, newValue: any) => void;
  private customProperties: any;

  constructor(elem: HTMLElement, properties: any, onPropertyChange: (propertyPath: string, newValue: any) => void, targetProperty: string, customProperties?: any) {
    this.elem = elem;
    this.properties = properties;
    this.onPropertyChange = onPropertyChange;
    this.targetProperty = targetProperty;
    this.customProperties = customProperties;
  }

  public render(): void {
    const element: React.ReactElement<IDatePickerProps> = React.createElement(DatePicker, {
      label: this.customProperties.label,
      value: this.properties[this.targetProperty],
      onSelectDate: this.onDateChanged,
    });

    ReactDom.render(element, this.elem);
  }

  private onDateChanged = (date: Date): void => {
    this.properties[this.targetProperty] = date;
    this.onPropertyChange(this.targetProperty, this.properties[this.targetProperty]);
    this.render();
  }

  // Other required methods from IPropertyPaneField
}

4. In your web part's property pane configuration, use the PropertyPaneCustomField to add the date picker:

typescript
protected getPropertyPaneConfiguration(): IPropertyPaneConfiguration {
  return {
    pages: [
      {
        header: {
          description: 'Custom Fields'
        },
        groups: [
          {
            groupName: 'Settings',
            groupFields: [
              PropertyPaneCustomField({
                targetProperty: 'selectedDate',
                onRender: (elem: HTMLElement): void => {
                  if (this.context.propertyPane.isRenderedByWebPart()) {
                    const datePickerField: DatePickerField = new DatePickerField(elem, this.properties, this.onPropertyPaneFieldChanged, 'selectedDate', { label: 'Select a date' });
                    datePickerField.render();
                  }
                }
              })
            ]
          }
        ]
      }
    ]
  };
}

5. Make sure to update your web part's interface to include the selectedDate property:

typescript
export interface IYourWebPartProps {
  selectedDate: Date;
}

With these steps, you have added a custom date picker field to your web part's property pane using the PropertyPaneCustomField control and the office-ui-fabric-react library.