When I start parity it automatically choses port 8180 to run upon. I currently try to follow this tutorial in building a small demo app: https://tomusdrw.github.io/parity-dapp-example/#/4/1

However all the rpc-calls that are executed by this app go to the 8080-port (which seems to be the standard port). How could I fix this?

I read here https://github.com/ethcore/parity/wiki/Basic-Usage that there is a --dapps-port PORT option. But when I use it starting of the node fails with this error message:

ERROR: Signer: Could not start listening on specified address. Make sure that no other instance is running on Signer's port. Details: Error { repr: Os { code: 48, message: "Address already in use" } }

wrong port when running parity

  • It's unclear what's the issue here. Why is 8080 a problem, and what port are you trying to use instead?
    – q9f
    Mar 13, 2017 at 13:41

1 Answer 1


I'll give it a try to answer based on what I think your question might be. First, a note: The DApps do not talk to the RPC API (:8545) but the DApps API (:8080).

If you want to change your dapps port from :8080 (default) something else, let's say :13337, run parity with:

parity --dapps-port 13337

If you get any errors, try another port, i usually just hit random 5-digit numbers greater than 33333 and will usually get a free spot.

If you want to change the port of the UI which displays your DApp from :8180, you can do it with:

parity --ui-port 42355

Now you will be able to access the DApp in your browser via localhost:42355. You can also do stunts like swapping the ports, i.e.,

parity --ui-port 8080 --dapps-port 8180

if this is your intention, but make sure you don't confuse yourself with this :) I hope this helps.

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