Rithmic session conflicts: one session per login
You press Test on a Rithmic connection and it answers "copier is running on this Rithmic login: stop it before testing (Rithmic allows one session per login)". Or the copier stopped on its own with the message "Rithmic signed the copier out: the same login connected somewhere else". Both are the same rule surfacing.
Why it happens
Rithmic caps how many sessions one login may hold, and when a login connects again past the cap it forces the oldest session out. That is not a network drop. It is Rithmic saying the login is now in use somewhere else: R|Trader, your prop firm's platform, another copier, or a Test you just pressed.
Most disconnects make MirrorFill reconnect automatically. A forced logout is the one drop where it deliberately does not. If the copier logged straight back in, it would force the other session out; that app would reconnect and force ours out again, and the two would ping-pong the login between them, and Rithmic can disable a login that logs in and out too many times. So the copier stops, stays stopped, and tells you why. The state pill in the top bar only ever says one word, and here it says Stopped, in amber rather than the neutral idle colour. The reason itself arrives on the surfaces built to carry it: a notification at the top right at the moment it happens, which stays on screen until you dismiss it, the same line in the Notifications panel (the bell at the top) and in Recent activity afterwards, and (if alerts are on) an e-mail sent immediately, without the usual disconnect debounce. Your positions are untouched: they live at the broker, and a stopped copier closes nothing.
The Test button follows the same rule in the other direction: a test is its own Rithmic session, so testing the login the running copier is using would force the copier's own session out. MirrorFill refuses that test and tells you why instead.
The rule also holds between MirrorFill accounts. Every account runs its own copier, and one Rithmic login (on one system) can drive only one of them at a time. If Test answers "This login is in use by a running copier, so it cannot be tested right now.", or Start copying says the broker login on a connection "is already in use by a running copier", a copier under a different MirrorFill account holds that login right now. Stop that copier first, or give each account its own login.
What to do
- After a forced logout, close the other app first. Sign out of R|Trader or whatever else took the login, then press Start copying. Starting without closing the other session just hands the login back and forth.
- Stop the copier before testing. Press Stop in the top bar, run Test, then Start copying again. Testing a login the copier isn't using needs no stop. On a phone, press Stop in the dock on the Desk tab first: the Accounts tab has no dock.
- Give the copier its own login where you can. If your firm offers separate logins, keep the copier on one and your own screen time on another. They stop competing for the same session.
Quick answers
Why doesn't the copier just reconnect after a forced logout?
Because the login is in use somewhere else, reconnecting would force that session out, and the two apps would knock each other off in a loop until Rithmic disables the login. A deliberate stop with a clear reason is recoverable; a login disabled by the broker is not.
Can I use R|Trader or my firm's platform while copying?
Not on the same login. Signing in elsewhere forces the copier's session out and the copier stops. Use a separate login if your firm offers one.
Rithmic disabled my login for logging in and out too much. Was that MirrorFill?
Not since forced-logout handling shipped: MirrorFill never reconnects into a taken session, so it cannot participate in the login ping-pong that triggers those blocks. Check for two other apps sharing the login.