The latest version of Nextion Editor can be downloaded [here]

To maintain code compatibility with projects created with version 0.53 or prior, an LTS Edition (Long Term Support) of the Nextion Editor can be downloaded [here]. The LTS Edition is not an excuse to be fearful of creating a new HMI project in the newer versions of the Editor (just as you were not fearful to create your current HMI).

If reverting back to the LTS Edition for code compatibility, or an earlier Nextion Editor version, use your “backup copy” of your HMI file that you backed-up before installing and trying out new software. If you forgot to make a backup (no-no-no tsk-tsk), open the “Version backup folder” and copy your old HMI file from the folder to use (and thank the Nextion Editor that it made a backup before converting into the new Editor version format).