Etcher is unresponsive and can't be used.
The Error:
TypeError: Expected a number
at prettyBytes (/tmp/.mount_OSOdsn/usr/bin/resources/app.asar/node_modules/pretty-bytes/pretty-bytes.js:18:10)
at module.exports.getDrivesSubtitle (file:///tmp/.mount_OSOdsn/usr/bin/resources/app.asar/generated/gui.js:7477:14)
at fn (eval at compile (/tmp/.mount_OSOdsn/usr/bin/resources/app.asar/node_modules/angular/angular.js:15351:15),
at expressionInputWatch (/tmp/.mount_OSOdsn/usr/bin/resources/app.asar/node_modules/angular/angular.js:16352:31)
at Scope.$digest (/tmp/.mount_OSOdsn/usr/bin/resources/app.asar/node_modules/angular/angular.js:18002:34)
at Scope.$apply (/tmp/.mount_OSOdsn/usr/bin/resources/app.asar/node_modules/angular/angular.js:18280:24)
at /tmp/.mount_OSOdsn/usr/bin/resources/app.asar/node_modules/angular/angular.js:20127:36
at completeOutstandingRequest (/tmp/.mount_OSOdsn/usr/bin/resources/app.asar/node_modules/angular/angular.js:6274:10)
at /tmp/.mount_OSOdsn/usr/bin/resources/app.asar/node_modules/angular/angular.js:6554:7
at wrapped (/tmp/.mount_OSOdsn/usr/bin/resources/app.asar/node_modules/raven-js/dist/raven.js:444:21)
It could have something to do with opening Etcher twice very quickly after each other (KDE does not require double clicks for opening... took some getting used to). It did work normally the last 2 times I tried.
I am getting the exact same error every time I start Etcher on Solus after upgrading to the latest version, see picture below:

I did get this too , but rightclicked on the file , > preferences > set all rights to 'read and write' and enabled "make it run as a program" (translated from dutch :-) )
This way it works like it should
Where do you find the file? Having the same error on Etcher but not understanding where to find it as it isn't in usr/share/applications as normal.
When you extract the zip file you've downloaded from the etcher website https://etcher.io/ you'll get a etcher,app image file. That's the file i've used
Same on Ubuntu 16:

Same here. I'm guessing something to do with pretty-bytes module
Seems to be related to read/write permissions given to etcher before running it.
Did you all try this procedure https://github.com/balena-io/etcher/issues/2508#issuecomment-432415759 ?
The same thing happened to me after I installed the .desktop file when I ran the .appimage file. The way I fixed it was to delete the file appimagekit-Etcher.desktop which is in the path: ~/.local/share/applications
Seems to be related to read/write permissions given to etcher _before_ running it.
Did you all try this procedure #2508 (comment) ?
Doesn't work for me.
I have tried appimage (with #2508 procedure) and deb installer. Both result in "expected a number".
We chased down the issue and it seems to go all the way back to nodejs itself, which has been fixed in new nodejs versions.
We're working on updating electron used by etcher so we'll include the newer nodejs versions and fixes
I was using the Solus repo version and the thing is that they are building with NodeJS version 8. In what version can the bug be found? Or will this simple get fixed with electron getting updated? @thundron
I still have it on ubuntu 18.04
EDIT: It worked when I installed with the .deb following https://github.com/balena-io/etcher#debian-and-ubuntu-based-package-repository-gnulinux-x86x64
I only ran into this issue when attempting to "launch/open" the AppImage via the quicksearch Super menu in Gnome (Ubuntu 18.04). If I instead opened "Files" and ran the AppImage from Nautilus (Gnome file explorer) it ran correctly.
I just changed the permissions on the Iso file and the application downloaded to 777 and it worked, i think you can debug with the permissions and get the problem.
Most helpful comment
I still have it on ubuntu 18.04
EDIT: It worked when I installed with the .deb following https://github.com/balena-io/etcher#debian-and-ubuntu-based-package-repository-gnulinux-x86x64