rexenv won't open

On macOS and Windows almost every “it won’t open” is the operating system refusing an unsigned build, not a bug — and it is a one-time step. rexenv is open source and earns nothing, so it buys no code-signing certificate. Linux has no such gate; there it is almost always a missing library or a desktop without a tray.

macOS

“rexenv can’t be opened” / “unidentified developer”

This is expected on the disk-image install. rexenv is ad-hoc code-signed and not yet notarized by Apple, so Gatekeeper blocks the first plain double-click.

Right-click (or Control-click) rexenv in Applications → Open → Open again in the dialog.

If you already double-clicked and got blocked: System Settings → Privacy & Security, scroll down to the rexenv message, Open Anyway, then Open.

After once, rexenv opens normally from then on.

Installing with Homebrew skips this

The cask removes the quarantine attribute during install, so there is no first-launch dialog at all — and rex lands on your PATH while it is there. See Install.

“The app is damaged and can’t be opened”

Same cause, different wording: macOS is reporting the quarantine attribute on a downloaded file, not actual damage. The right-click → Open above clears it.

If you want to confirm nothing is actually wrong with the download, check it against the published checksum:

shasum -a 256 -c rexenv_*_universal.dmg.sha256

Nothing happens at all

First, look at the menu bar, not the dock. rexenv has no dock icon: a launch puts a crowned-R icon in the menu bar, and Open rexenv in its menu shows the window. A launch from Start rexenv at login deliberately opens no window at all. If the icon is there, rexenv is open.

If there is no icon either, check your macOS version — rexenv needs macOS 13 (Ventura) or later (0.8.6 and earlier needed 15):

sw_vers -productVersion

Below 15, rexenv installs and then cannot share a site, because the pinned cloudflared build will not launch there. See Requirements.

It opened the wrong version

macOS finds an app by its bundle id, not by where it sits. A second copy of rexenv.app — an old one in Downloads, a build left in a project folder — means open -a rexenv, Spotlight and the login item can all start the copy you did not mean. Both copies share the same data folder and the same services, so the symptom is not two apps: it is one app that is the wrong version. rexenv refuses to run twice against one data folder, so the second launch just brings the running copy to the front. Keep exactly one copy, and drag the old one to the Trash after updating.

Windows

“Windows protected your PC”

This is expected, and it is SmartScreen rather than an antivirus verdict. The installer carries no code-signing certificate, so Windows blocks an app it does not recognise.

Click More info — the same dialog then names the app and Publisher: Unknown publisher, and grows a Run anyway button. That starts the installer directly.

A new release is a new file hash and goes through it again. Reputation accrues per hash; a certificate would skip it, and rexenv does not buy one.

“The publisher could not be verified”

A different, shorter dialog — Open File - Security Warning — with Run on the first screen and no “More info” to find. It is what a machine with SmartScreen switched off by policy shows instead. The two are alternatives, not a sequence.

Edge won’t let you keep the download

“…isn’t commonly downloaded. Make sure you trust it before you open it.” — Keep is behind that download row’s See more menu.

To confirm the file is the one rexenv published, check it against the published checksum. It answers True, or it answers False:

(Get-FileHash .\rexenv_*_x64-setup.exe -Algorithm SHA256).Hash -eq (Get-Content .\rexenv_*_x64-setup.exe.sha256).Split()[0]

“rexenv is still running” during install

The full prompt: “rexenv is still running: the app, or the small background resolver that keeps your .rex sites answering after you quit. Click OK to stop it and continue.” Installers up to 0.8.5 said “rexenv is running! Click OK to kill it” instead.

You are installing a newer build over an installed one, and the .rex DNS answerer is the same rexenv.exe — so it is running even with the window closed and rexenv quit. OK is right: it comes back on the new build a few seconds later, started by its logon task, and .rex keeps resolving throughout.

If it answers “Could not stop rexenv” instead, end every rexenv.exe in Task Manager — the app and its background resolver — and run the installer again.

Nothing happens at all

Look at the tray, not the taskbar. rexenv is a tray app: left-click the icon opens the window, right-click opens the menu. If the icon is there, rexenv is open.

If there is no icon, check that you are on a supported Windows — 11 x64, with 10 22H2 best-effort:

Get-ComputerInfo -Property OsName, OsVersion, OsArchitecture

An arm64 machine runs the x64 build under emulation, which is unsupported: the PHP and PostgreSQL builds rexenv needs have no arm64 Windows version. See Requirements.

Linux

The AppImage does nothing, or says it needs FUSE

An AppImage mounts itself with libfuse2, and Ubuntu 22.04 and later do not install it by default. Install it, or run the AppImage unpacked:

sudo apt install libfuse2        # libfuse2t64 on 24.04 and later
APPIMAGE_EXTRACT_AND_RUN=1 ./rexenv_*.AppImage

The .deb has no such step, and neither does the one-command install, which installs the rexenv package wherever apt exists.

apt refuses the package

On Ubuntu 20.04 the package cannot install: it needs libwebkit2gtk-4.1-0, which 20.04 does not have — 22.04 is the first LTS that does. The one-command install says so before it downloads anything:

rexenv needs Ubuntu 22.04 or newer (its webview is libwebkit2gtk-4.1); this is Ubuntu 20.04.6 LTS.

Check what you are running:

. /etc/os-release && echo "$PRETTY_NAME" && dpkg --print-architecture

An amd64 package on an arm64 machine, or the reverse, is refused by apt for the same reason it should be: pick the file whose name matches dpkg --print-architecture.

Nothing happens at all

Look at the top bar, not the dock. rexenv is a tray app: its icon’s menu — any click opens it — carries Open rexenv. A launch from Start rexenv at login deliberately opens no window.

Launching rexenv again brings the window back: the running copy answers, rather than a second one starting. That is also the way in on a desktop that shows no tray icons at all — Ubuntu’s GNOME shows them, and a desktop without appindicator support does not.

The password dialog never appears, or is refused

Every system change goes through pkexec, which needs a polkit authentication agent — any desktop session has one; an SSH session or a bare terminal does not. Without one, or on an account polkit does not count as an administrator, rexenv says:

This account is not allowed to administer the computer (polkit refused), or no authentication agent is running.

Dismissing the dialog is not an error to fix: “Administrator permission was cancelled — this step needs it. Try again and approve the prompt.” Nothing was changed, and the step is offered again.

It opens, but nothing will start

That is a different problem from this page — the app is running and something in the stack is refusing. From a terminal:

rex doctor

It reports what is wrong and, where a fix exists, what to do about it. The most common answer is that another program already holds port 80 or 443 — often a system nginx or Apache, IIS, or another local dev environment that is still running.

Still stuck

Open an issue at github.com/rexenv/rexenv, and include the output of rex doctor and your operating system version. Those two answer most of the first round of questions.