Error: Failed to receive commit notification for transaction

[admin]

I know I'm normally supposed to be the one answering questions here but I am stuck. When making a GET request to my composer-rest-server, everything works fine. POST requests, however, are returning this:

Code:

Unhandled error for request POST /api/org.sample.network.buyCar: Error: Error trying invoke business network. Error: Failed to receive commit notification from localhost:7051 for transaction within the timeout period

System Details
Hyperledger Fabric v1.2
Hyperledger Composer 0.20.0
Ubuntu 16.04

[huangxiaojun24]

I also have same problem, do you fix it?