Hi Sravanthi,
Greetings from Syncfusion support.
This issue may occur because of the Syncfusion control’s PHP package was not referred properly in your application.
Syncfusion controls PHP packages can be found from build installed location, please find the default path of this location.
C:\Program Files (x86)\Syncfusion\Essential Studio\PHP\{version}\PHP\Src
To include the Syncfusion controls in your application, you need to add the files inside the Src folder into your application.
We have prepared a Gantt sample by placing files inside the folder named EJ and referred in web pages.
Please find the sample link below.
You can get the PHP package only from build installed location, please get back to us if you require further assistance on this.
Regards,
Jesus Arockia Sankaran S