Web Dev doPost Example giving me an error

I’m trying to do a doPost and I’m following the example linked below, but I’m getting a weird error:

Server returned HTTP response code: 500 for URL: http://localhost:8088/system/webdev/arduino_project/postjson

Can anyone help me with this?

The example:

This is the code for my doPost:

data = request['postData']
	names = data['names']
	values = data['values']
	# this will print to the wrapper.log file
	print names, values
	# format the string into HTML
	formattedString = "<html><body>"
	# loop through and add names and values
	for i in range(len(names)):
	    formattedString += "%s: %s, " %(names[i], values[i])
	# remove the last ', ' and add closing html
	formattedString = formattedString[:-2]+"</body></html>"
	# this will print to the wrapper.log file
	print formattedString
	# return the value string
	return {'html': formattedString}

This is the code for my button:

projectName = "arduino_project"
doPostName = "postjson"
url = "http://localhost:8088/system/webdev/arduino_project/postjson"
# create the dictionary of parameters to pass in
params = {}
params['names'] = ['String','Integer']
params['values'] = ['Hello World', 42]
# encode dictionary to JSON
jsonParams = system.util.jsonEncode(params)
# post to Ignition
postReturn = system.net.httpPost(url, jsonParams)
# print return value
print postReturn

I appreciate any help!

In your button code you typed in the wrong url.

The url should be the following.

url = "http://localhost:8088/main/system/webdev/%s/%s" %(projectName, doPostName)

Notice the /main/ before /system/