Thanks for pointing me in the right direction. I tried this again, and am getting the same issue. I rebooted, tried to launch the batch script with the IDE closed, and then from within the Arduino IDE. I am getting the same error. Here’s the updated sketch:
#define BLYNK_PRINT SwSerial
SoftwareSerial SwSerial(10, 11); // RX, TX
char auth = "mytok";
// You can inject your own code or combine it with other sketches.
// Check other examples on how to communicate with Blynk. Remember
// to avoid delay() function!