Help For You: Trouble shooting starting the new version (can't get it started)

A lot of people have a hard time when updating.

Here are some tips that might help you.

1- If you are syncing but an your machine says something like “NIS is synchronizing. At block 221896, est. 126 days behind. (at block 221896)” and doesn’t move and sync but seems stuck, please try to delete your database and start a new chain. You can speed up this process by just downloading a new chain and inserting it manually. Here are some tutorials with step by step instructions.

2- If there is a major problem, you might have to delete all NEM software on the computer and start over from scratch installing. Here is a tutorial for that.

Generally speaking the installer is the most buggy. Most people that have a problem with the installer find that using the stand alone works. Instructions for the stand alone are here.

If you have your private key backed up, or want to make a new wallet with a pass phrase, the Lightwallet is also very safe and easy to use.

At some point NEM will fully transition away from NCC to Lightwallet and mobile apps for iOS and Android and there will no longer be any of these problems.

3- If you are having trouble logging in.

Go to C:\Users\yourname\nem\ncc and delete the ncc.cfg file and the accounts_cache_mainnet.json file.
4. If NIS wont start. Go to C:\Users\yourname\nem and delete the nis.lock file.

5- If you are having a problem with Java, please try to update your Java.


If you are getting this Java error when trying to install the NEM installer, then you will need to delete and reinstall Java.

Doing the automated reinstall won’t fix the problem. Please go to Control Panel -> Programs -> Java -> Delete Java

Also go to C:\Program Files (x86) and look for any old Java programs there and delete them.

You will need to download the 64 bit version of java as the installer only works on 64 bit OS and 64 bit Java. Please go to and download a 64 bit version exe and install it.

That should work and you can now install the NEM installer.

If it doesn’t, you might want to look at your Java pathway and edit it as described here.

Some people are having problems with their node being unresponsive. This can be because of RAM settings. For the short term to help minimize this problem please do the following.

Go to package -> NIS ->

Then change the level on the first and third entry from “INFO” to “WARNING” and restart NEM.

The should look like this.

Hi Jabo38,
I want to use the lightwallet. It asks for a few things:

  1. wallet name
  2. account address
  3. private key
  4. password

i know 2 en 4.
I have a wallet file like: london.wlt.
is the wallet name the same as london? and is there a way to retreive the private key from the wallet file?


More tips from Pat.

Some people who run a Supernode for an extended time will have log files build up. If you want to auto-delete your log files to save space, you can follow the advice from Rev in the Telegram chat.

you can always add to the startup script or a cron find ~/nem/logs -ctime +10 -delete

Here is the answer to that 699 problem.

Sometimes people update and they have a problem with NCC starting. If that is so then do the following:

Delete the file accounts_cache_mainnet.json in the folder c:\users\ < your_user > \nem\ncc.

Then start ncc again.