Problems with a Web site cluster environment

I am a mobile application site, in the production environment is deployed in an Nginx implementation of 3 servers to load.

In the last two weeks, product managers have been reflecting that some of the customer service personnel visited one of the "order Management" functions reported as follows error:

Since it has not been in line for nearly two weeks, the initial suspicion is that the program file version of the 3 servers on the line is inconsistent.

Every day is a lot of things, I did not find ops to verify. Every time the product asks this thing, I always stall.

Yesterday coincides with the online day, to find operations and maintenance verification. After checking, sure enough, there is a server node on the program version of the old, may be some time on the line, forget to overwrite this node. When the program files are unified, they are all peaceful.

Problems with a Web site cluster environment