Error in importing specctra session (Msg: Board may be corrupted)

I have followed the following steps:

  1. Create the schematic in Eschema.
  2. Annotated the components
  3. Associated the components with their corresponding footprints.
  4. Generated a netlist.
  5. Opened the netlist in PCBNEW and then exported as Specctra DSN format
  6. Opened the DSN file in FREEROUTING
  7. Ran AUTOROUTER (successfully got the routing traces as expected)
  8. Exported auto-routed design as Specctra Session file

PROBLEM: The exported specctra file is of 0 bytes. I don’t what is going wrong here. Then once, I import the .sess file back to PCBNEW, it is throwing the following error.

Board may be corrupted, do not save it. Fix problem and try again
Expanded Error: Expecting " '(' " in input/source "/home/projectfolder/myPCB.sess" line 1, offset 1

NOTE: I am running this entire project on Ubuntu 20.04. And I am using Freerouting version v1.4.5-SNAPSHOT(build-date:2021-10-25)

Well I guess you should find out why FreeRouting isn’t generating a SES file. Maybe raise an issue at its GitHub project page? The project is not associated with KiCad.