Web IDE: connects but gets RECEIVE ERROR: {"connectionId":14,"error":"frame_error"

I am able to connect via COM3 to my ESP8266, flashed with 1.87, 115000 baud, but cannot see replies to the text sent to device. Please advise on how to resolve

ERROR: RECEIVE ERROR: {"connectionId":14,"error":"frame_error"}
Disconnect callback...
>>> Disconnected
>>> Connecting...
Set Slow Write = true
[object Object]
Connected [object Object]
Found a prompt... great!
>>> Sending...
---> "echo(0);\nconsole.log(\"<\",\"<<\",JSON.stringify(process.env),\">>\",\">\");echo(1);\n"
Sending block "echo(0);\nconsol", wait 50ms
Sent
Sending block "e.log(\"<\",\"<<\",", wait 50ms
Sent
Sending block "JSON.stringify(", wait 50ms
Sent
Sending block "process.env),\">", wait 50ms
Sent
Sending block ">\",\">\");echo(1)", wait 50ms
Sent
Sending block ";\n", wait 50ms
Sent
>>> Sent
WARNING: No result found - just got ""
Device found (connectionId=15)
>>> Connected to port COM3