Manual / Reference / TroubleshootingiCity 2 · Windows

Troubleshooting

Sorted by what you can see, not by what is at fault. Before anything else, open the Logs editor — it sits under the iCity Editor in the “iCity 2” workspace, and the strip along its top says whether the engine is alive and how much of its restart budget this session has spent. Most of what follows is visible there first.

Nothing responds

Almost everything in this section is one fact: the engine is stopped. Draft is entirely dispatched to it, so with it off the interface withdraws the tools rather than offering handles onto nothing.

troubleshooting-engine-stopped.png

The iCity Editor in Draft with the engine stopped and a project open, in any mode other than Graph: the tool rail empty, the message 'The iCity engine is not running. Start it to edit your city.' with the Start Engine button beneath it, and the 3D viewport beside it showing the city with no selection gizmos drawn. Frame the Blender status bar too, so the absent D / G / Del hints are visible.

/docs-shots/blender/
What a stopped engine looks like: no tools, no gizmos, and the line that says why.
What you seeWhat to do
The tool rail is empty, the selection gizmos are gone, and the status bar shows no D / G / Del hints.The engine is stopped. Every Draft mode except Graph says so: “The iCity engine is not running. Start it to edit your city.” Press Start Engine under that line. See The engine.
The Logs editor reads “Restart budget exhausted (3 attempts) — engine stopped”.The engine crashed, was restarted automatically three times, and the budget is spent. Nothing restarts it now. Press Start Engine again — your saved city state is reloaded on the way up.
The engine says it is running but the viewport stays empty. The console reads “the engine is running but EMPTY. Stop/Start the server to reload the city.”Do exactly that: Stop, then Start.
Start reports “Binary not found:” with a path, or “Core failed to start.” with console output.The engine is iCity2App.exe in Addon/bin/windows/, with iCity2Client.dll beside it. Security software quarantining or blocking either produces both messages. Exclude them and start again.
Selection works, but the width, node and floors drag handles have disappeared.Blender's own Move, Rotate or Scale tool is active. The handles only draw while Blender's Select tool (Tweak, Box, Circle or Lasso) is the active tool.
Clicking a city object selects nothing at all.City objects have Blender's own selection switched off; picking happens through the gizmos. If the rail's Select button is unlit, click it — clicking a lit Select switches selection off, and so does “Hide gizmos in <Mode>” from the ⋮ menu.
A drawn shape reports “engine busy or not running — nothing generated”.The stroke was refused, not queued. It is gone. Wait for the engine to settle and draw it again.
Draw Region produced nothing.A drawn region must overlap at least one Buildings-typed block — a polygon that misses every eligible block is a no-op — and it must cover at least one square metre; under that it reports “Draw Region: too small (under 1 m²)”. A busy engine is retried in the background for about four seconds, then the console says “engine stayed busy — draw DROPPED, please redraw”.
Ctrl+Z undid a Blender action instead of your city edit.iCity owns Ctrl+Z only while your most recent action was an iCity edit; anything else hands the key back to Blender. It also stands down mid-drag and while a mesh is in Edit Mode.
The “iCity 2” workspace tab is gone.No button re-creates it. The addon re-creates it on file load when it is missing, so save and reopen the file. If the tab is there but an area shows the wrong thing, pick iCity Editor or iCity Logs from that area's editor-type selector.
Stop is missing from the header while the engine is running.A narrow editor region sheds header controls to fit. Widen the iCity Editor area.
There is no Scatter tab, or Alt+6 gave you a mode with no tools.Scatter is a Design mode; Draft hides its tab. Switch the header toggle to Design.
Note

The Logs editor prints the engine's state as a word and a count: inactive (not running), monitoring (alive), activating (restarting), crashed, followed by restarts n/3. Cloud job lines never appear here — they live in the Design composer's thread and the Cloud Activity popup.

troubleshooting-logs-restart-budget.png

The iCity Logs editor in the 'iCity 2' workspace after the engine has crashed and auto-restarted three times: the strip along its top reading the state word 'crashed' with 'restarts 3/3', and the line 'Restart budget exhausted (3 attempts) — engine stopped' in the log body with a few lines of ordinary engine output above it for context.

/docs-shots/blender/
The Logs editor after the restart budget is spent — the state word, the count, and the line that ends it.

I cannot sign in

Signing in happens in your browser and comes back to Blender over a local port. Most failures are that return trip, not your password.

What you seeWhat to do
The browser says “this page can't be reached” after your password was accepted.The addon listens on http://127.0.0.1:9876/callback for the answer and the browser could not reach it. Close other copies of Blender, then check whether a firewall or antivirus is stopping Blender from listening, and sign in again.
Blender reports “Could not open port 9876 to receive the sign-in… Another program may be using it, or a firewall or antivirus may be blocking Blender from listening.”The port is held or blocked. Only one Blender can hold it at a time. Close the others and retry.
“Login timed out.”The addon waits five minutes for the browser and then gives up. Press Login again. The header Cancel (or Esc) abandons a sign-in you no longer want.
There is no Sign up anywhere in the addon, and the hosted page will not create an account.Self-service sign-up is switched off for the account pool. The addon signs in to an account that already exists; accounts are created through parametra.net.
The Draft/Design toggle is disabled: “Sign in to access the Design module”.Design needs a signed-in account and a city in the scene. Sign in from the header Account button. Logging out drops you back to Draft.
The footer sync button is a red “!”: “This project needs server access and you are not signed in — sync is paused. Click to sign in.”Click it. The flag starts the sign-in it is complaining about.
A job fails with “Session expired”.The token stopped being valid. Sign in again and resubmit — no credits were charged, and your prompt is preserved.

My city is gone

Your city is not your .blend. It lives in the engine process and is written to Documents/iCity 2/<project> by the header S button — Blender's own save does not reach it. How iCity fits with Blender is the full explanation; these are the ways it bites.

What you seeWhat to do
You reopened a saved .blend and the city is missing, or is there but not editable.Nothing opens by itself on file load — no project is opened and no city state is restored. Use Open Project from the launch screen. A .blend holding no initialized project also drops the engine's cached city state as it loads, so Open Project is the only way back.
You pressed S and nothing was written.The log reads “Nothing to save yet — the engine has not written a city state. The project stays open.” Start the engine and make an edit, then press S.
You closed the project and the city vanished from the scene.Closing clears the city and stops the engine; the folder on disk is never deleted. Open the project again to get it back. “Close without saving” and the header X discard unsaved changes.
You expected an automatic project upload and nothing uploaded.There is no automatic project upload. The call that used to arm one is a deliberate no-op, and the footer's Auto/Manual arrow is gone. The footer Sync button is the only thing that uploads, and it asks you for a message first. See Saving, syncing, versioning.
Sync refuses: “this folder is showing version x.y, so it is read-only — open the latest version to make changes”.You are on a checked-out older version. Open the latest version of the project and work there.
Sync refuses: “this project isn't on the server yet — use the warning button in the footer to upload it”.The folder has no server record, which is normal for a project made while signed out. Click the footer's red “!”.
The footer shows “This project cannot identify itself — click to fix it”.project.json holds only the server id, and it is missing. Click the flag and choose to upload it as new or adopt the existing record. The editor repairs it by itself within a few seconds if this session still knows the id.
Creating a project failed and the folder is left unregistered.A name already used on your account is refused rather than silently adopted. Rename the project, or use the identify dialog to point the folder at the right record.
Blender quit before you pressed S.Quitting banks the live city into the active project folder on disk. It does not upload anything.

Something says UNSYNCED

UNSYNCED appears beside the object name in the selection header. It means that object is locked: frozen out of procedural editing. The engine's re-emits skip it, the gizmos ignore it, and it becomes normally selectable with Blender's own tools instead.

troubleshooting-unsynced-header.png

Close crop of the selection header in the iCity Editor with a single locked building selected, so the object name is followed by the UNSYNCED marker. Capture in Massing mode so the section beneath shows 'Floors: procedural buildings only' in place of the floors stepper.

/docs-shots/blender/
UNSYNCED beside the object name in the selection header.
What you seeWhat to do
UNSYNCED in the header, and floors, type and reshaping do nothing on that object.That is the lock working as designed. Draft edits are not reaching it, and a full Regenerate will not reclaim it either — the engine's re-emit deliberately skips locked objects.
You want to know how it got locked.Nothing in this build locks objects: sending a theme no longer unsyncs the city, and the lock button was removed. A lock you see today was carried in from a file dressed by an older build, or set with the Lock / Unlock operator.
You want it back under procedural control.The operator that does it is Sync: it unlocks the selection and regenerates so the procedural system reclaims it. That object's hand edits are regenerated over — that is what re-syncing means. No button in this build calls it; it is reachable only through Blender's operator search.
The floors stepper is replaced by “Floors: procedural buildings only”.Floors are offered on engine-generated buildings only. The control is dropped for locked objects, for the ground sheet and prop-path helpers, and outside Massing mode.

The dress looks wrong

City sync — the header pair, not the footer one — is the automatic side, and it is on by default. It fires about two seconds after you return to Design with a changed draft, it re-dresses with the theme you already have, and it spends credits doing so. The ▾ beside the button switches it to Manual.

troubleshooting-grey-cubes.png

The 3D viewport with a scatter shape just drawn by a system that has no assets in its objects row, so the shape is filled with uniform grey placeholder cubes. Show the Scatter tab beside it with that system's objects row expanded and empty, its '+' button visible.

/docs-shots/blender/
A scatter system with no assets yet: the drawn shape comes back as placeholder cubes.
What you seeWhat to do
You changed the draft and Design still shows the old dress.City sync refuses when the draft has not actually changed, and waits for the button when its ▾ is set to Manual. Press the header sync button. See Re-dressing after a change.
The log reads “City sync needs a 3D viewport in the iCity workspace — skipped.”The sync exports from a 3D viewport. Open one inside the “iCity 2” workspace.
A send is refused: “Could not export the city … Switch the collection back on in the Outliner and send again.”A collection switched off in the Outliner is not in the view layer, so its objects cannot be selected and miss the export. Switch it back on.
The Materials section says “No material categories for this mode.”Your library holds none of the categories that mode dresses. Generate or download a theme first, then come back.
“Start with default theme” left grey geometry or missing props.The bundled default project copies its outputs, assets.json and send files into your project. It does not download the materials and props they name — the linker resolves those from your local library and reports the fallback in the log.
“This build carries no default project”.The button copies a bundled theme out of a default_project folder inside the addon, and the copy you installed does not have one. Reinstall from the current download, or use Generate theme or Append from a project instead. See Themes.
The props “+” menu is empty: “No instancer groups yet”.Prop systems attach to the placements the linker builds. Dress the city first, then the menu lists them.
“This system predates the placement picker — make a new one to assign it.”That system was created before the scene had placements to offer. Delete it and add a new one.
A drawn scatter shape came back as grey cubes.The system has no assets yet, and until it has some a drawn shape scatters placeholder cubes. Open its objects row and add assets with “+”. The console says so at the moment you arm the tool.
Lane edits are ignored, or road widths stopped changing.A lane edit needs a single road segment selected; junction nodes and OSM roads are refused, and that message goes to the console only. With nothing selected you are editing the city-wide default. Once the city is dressed, the width reference is locked to Road and road widths no longer move from the lanes card.
A section's ⋮ menu (Copy to selected, Save as preset, Reset) does nothing.Those entries print “not wired yet” to the console. They are not connected in this build. The same is true of the OSM card's Clean OSM and Convert to iCity Geometry buttons — only Download OSM works.
Ctrl+Z after a dress does nothing.The linker suspends Blender's global undo while it dresses. You re-dress rather than undo. See What survives a re-dress.
“design state is v… this build reads v… — not loading (update the addon)”.The .blend was saved by a newer addon than the one installed. Its materials, systems and lane settings are left untouched rather than half-read. Update the addon.

A job never came back

Job tracking is session-only. Records live on Blender's window manager and polling runs in memory; nothing resumes after a restart.

troubleshooting-failed-job-thread.png

The Design composer thread after a submission was refused for credits: the prompt that was sent, followed by the failure entry printed as '402 — Not enough credits' with no further detail lines, and the send button back to an up arrow rather than a red stop square.

/docs-shots/blender/
A failed job in the composer thread: the code and the headline, and nothing else.
What you seeWhat to do
A theme job finished while Blender was closed.It cannot be recovered from the interface. Nothing restarts the polling, so the assets and outputs were never downloaded and no button fetches them. The credits were still spent. A theme takes about twenty minutes — leave Blender open across one.
The job completed, the outputs are in the project folder, and the city is still undressed.Close the project and open it again. The open path links outputs.csv once the engine settles, and it is safe to repeat — the pipeline clears what a previous link made rather than stacking on it.
The composer thread and the job list are empty after restarting Blender.Expected: those records are session-scoped and are not written into the .blend.
You closed a review popup with “Close (decide later)”.The job waits at that gate on the cloud, indefinitely. Return to the composer to make the decision, or press Stop to cancel it.
Stop reports “Marked cancelled, but the pipeline did NOT stop”.The record says cancelled but the run continues, and so does the bill. This is the one cancel outcome that is not a success.
Stop reports “Cancel refused” or “Cancel failed … the job is still running”.The local record is closed only when the server agrees, so the interface is telling you the truth. Try again, or check the job in Cloud Activity.
The composer thread shows only a code and a headline, such as “402 — Not enough credits”.Each failure records three parts — what happened, what it cost, what to do next — but only the code and headline are printed. A 402 charged nothing; free up credits or change plan and resubmit. See Credits & plans.
“Prompt rejected by content policy”.No generation credits were charged. Edit the prompt to remove the flagged content and submit again.
The Generate button is disabled: “Generate a city first — the theme is applied to your city (Draft module)”.A theme dresses a city that already exists. Draw or generate one in Draft first. See Generating a theme.
The estimate said about 219 credits and you were charged more.That figure is a fixed number in the popup, not a quote from the server. A full theme costs roughly 220–275 credits and takes about twenty minutes; measured runs have landed at 272–274. See Credits & plans.
Job progress does not match what the cloud is doing.The percentage in the step ladder is derived from which step is showing, not from the server's own progress figure. Use the step names, not the number.

My own assets do not appear

The scanner reads folders, never loose files, and it says nothing when a folder is shaped wrong — it simply contributes no assets. The layout is the whole contract:

text
<your folder>/
  materials/<Category>/<AssetName>/
      preview image  +  texture maps  (config.json optional)
  props/<Category>/<AssetName>/
      preview image  +  .blend / .glb / .gltf / .fbx / .obj
troubleshooting-custom-folder-layout.png

Windows File Explorer with the navigation pane expanded on a custom assets folder, showing the tree three levels deep: the root with its materials/ and props/ subfolders, a category folder open under each, and one asset folder open in the file pane holding its preview image and its texture maps or model file. Address bar visible so the path reads.

/docs-shots/universal/
A custom assets folder the scanner reads: one folder per asset, under a category, under materials or props.
What you seeWhat to do
Nothing from your own folder shows up in the browser.Check the layout above. One folder per asset, under materials/ or props/, under a category folder. A root with neither subfolder contributes nothing at all. See Using your own assets.
The browser says “No asset folder is configured yet — set one in the addon preferences”.Set Custom Assets Folder in the addon preferences. iCity only ever reads from it.
A prop is listed, but Assign is replaced by Generate Model.That prop folder holds no model file, and a prop without a model cannot be assigned. Add one, or generate a model for it.
Regenerate, Edit material or Edit prop refuse: “This is a local asset - it has no cloud identity.”Only assets downloaded from the cloud carry the id those actions need. Local and custom assets are read-only to the pipeline.
Turning on the Starred filter empties the view.Starring is a cloud-side favourite and needs a cloud id, so a custom-folder asset can never be starred. The filter is doing exactly what it says.
You changed the Library Folder and your generated assets vanished.Changing that preference does not move files. The Sync button beside it copies the old library across once and then deletes the old copy, and it only appears while the previous location is recorded and still exists.
Files you dropped into an asset folder are not there yet.The scan is cached and refreshed on a timer, so new folders appear on their own shortly after.
If it goes wrong

If none of the above matches, press Report in the header. It opens the report form with this session's log attached, and you can follow the reply under Account ▸ Contact us ▸ My cases.

Otherwise: the Discord is fastest for anything scene-specific, and Contact support suits licensing, billing and anything that needs a file attached.

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Nothing respondsI cannot sign inMy city is goneSomething says UNSYNCEDThe dress looks wrongA job never came backMy own assets do not appear
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