Sampat Kumar
Ansys Employee

Hi Reza,
Are you able to open this file in the 2023R2 now? 

Usually, this error indicates a corrupt file. To retrieve this file, visit the following link.

https://www.padtinc.com/2013/07/16/corrupt-ansys-mechanical-database-you-might-be-able-to-recover/

Without having to rerun the entire model, you can read the RST file right in the newly recovered file.

Let me know if this help you or not. 

Best Regards,
Sampat