Troubleshooting
Find what you're seeing below and follow the fix. Most problems are validation errors, and the message usually names the shape to fix.
What-if Analysis is greyed out
Hover over the button. It tells you the reason:
| What it says | What to do |
|---|---|
| Checking sign-in… | Wait a moment for Quodsi to finish checking. |
| Sign in to use What-if Analysis | Sign in from the strip at the top of the Quodsi panel. You need a free account. |
| Fix 2 validation errors before opening What-if Analysis | Open the validation list, as described below, and fix each error. |
Don't see the button at all? The page isn't a model yet. Convert it first with Convert Diagram to Model. In draw.io, you might see the message "Your model isn't ready yet — convert the diagram first."
Reading validation messages
Quodsi checks your model as you work. To see the results, click the small chip in the Model editor's header. Click an empty part of the diagram first, so that the Model editor shows.
| Chip | Meaning |
|---|---|
| Red ⚠ and a number | That many errors. You can't run until they're fixed. |
| ✓ and a number | The model can run, with that many warnings. It may run without doing what you meant, so read them. |
| ✓ alone | The model is valid. |
| Validate | Lucidchart only. Click it to check the model. |
Errors that stop a run
| Title | What it means | How to fix it |
|---|---|---|
| Missing required element | "Model must have at least one" generator, activity or entity. | Add the missing piece. If your diagram has the shape, select it and set its type in the panel. |
| Generator configuration error | Often "Generator must have an exit connector to route generated entities". The Generator has nowhere to send work. | Draw an arrow from the Generator to the first step. If an arrow is there, check it's a Connector and attached at both ends. The message can also name a bad value, such as an invalid time between arrivals. |
| Invalid connection endpoint | A connector points at a shape that no longer exists. | Reconnect the arrow, or delete it. |
| Invalid seed | The seed isn't a whole number from 0 to 2^64 - 1. | Use a whole number in that range. |
| Action count is too low | A Split or Join count is below 1, or a Loop count is below 0. A Split of 0 would delete the entity. | Raise the count. |
| Action has no Destination Activity | A Split, Create or Join has no destination, or the one it had was deleted. | Choose a Destination Activity. |
| Split goes back to its own Activity | A Split inside an Activity sends its new entities to that same Activity. | Choose another Destination Activity. |
| Join on a connector | Entities wait for a Join inside an Activity, so it can't run on a connector. | Move the Join to an Activity. |
| Activity loops back with no queue | A connector returns to its own Activity, and that Activity has no inbound or outbound queue, so an entity going round would wait for the slot it's already in. | Give the Activity an inbound or outbound queue, or route the rework through another step. |
| Activity loops forever | Every way out of an Activity leads back to itself, so entities can never leave. | Add a connector to another step, or remove the loop. |
| Invalid capacity | Capacity is below 1. | Open the Activity or Resource, and set capacity to 1 or more. |
| Invalid run length | "Simulation run length must be greater than 0". | Set Run Length on the Model editor's Basic tab. |
| Warm-up longer than the run | The warm-up must be shorter than the run, or nothing gets measured. | Shorten the warm-up or lengthen the run. See Warm-up. |
| Missing finish date | A calendar model has no start date. The finish is the start plus the run time. | Set the start date. |
| Duplicate name | Two elements of the same kind share a name. Results and scenarios identify elements by name. | Rename one so that each is unique. |
| Connector weights add up to zero | A step routes by probability, but all its weights are zero. | Give at least one connector a positive weight. They needn't add up to 100. |
| Negative connector weight | A connector has a weight below zero. | Set it to zero or above. Zero means that path is never taken. |
| Routing can't be satisfied | A step routes by entity type or by a condition, but none of its connectors define one. | Set the entity type or condition on a connector, or switch back to probability routing. |
| Invalid duration | A time can't be sampled as entered, for example a Uniform low that isn't below its high, a value that isn't a number, or a time between failures that can only be zero. | Open the step the message names and correct the numbers. |
| Move-time action has no duration | A connector has a move time with no value. | Enter a duration, or remove the move time. |
| Negative cost value | A cost field is below zero. | Set it to zero or above. |
| Invalid resource requirement reference | A step uses a resource requirement that no longer exists. | Choose an existing requirement on the step. |
| Work schedule not found | A Resource or Activity follows a schedule that's been deleted. | Choose another schedule, or go back to fixed capacity. |
| State expression is invalid | An expression can't be read, or it names a state that doesn't exist. | Check the spelling and the state's type. Only entity and model states can be read in an expression. |
Warnings worth reading
| Title | What it usually means |
|---|---|
| Element has no connections | The step has no incoming or outgoing connector. If you drew arrows, they may not have been converted. Select each arrow and choose Connector in the panel's type dropdown. A step with no way out is fine if that's where work leaves the process. |
| Isolated element | The shape isn't connected to anything. Connect it or remove it. |
| Activity has no actions | Entities pass through instantly, with no delay and no resource use. Add a time if the step takes time. |
| Requirement asks for more than its resources have | A step needs more units than its resources have, so no amount of waiting could meet it. Lower the Quantity, raise the resource's Capacity, or add an alternative that fits. |
| Resource never released | A step takes a resource and doesn't give it back. Add a Release action, or use Delay-with-Resource. Release must name the same requirement that seized the resource. |
| Resource not used by any activity | The resource has no effect on the run. Have a step use it, or remove it. |
| High entity generation rate | Work is arriving very fast. Check the units on the time between arrivals. |
| Duration draws below zero | Some draws of a time fall below zero and count as zero, so its average is higher than the distribution's mean. The message gives the real average. Move the distribution above zero if that isn't what you meant. See Randomness and replications. |
| Missing name | Give the element a name, so that it reads clearly in reports. |
Converting a diagram
| What you see | What to do |
|---|---|
| "no shapes classified", or shapes skipped | Quodsi reads how shapes connect, and it skips a shape with no arrows. Attach your arrows to shapes at both ends, then convert again. Or set a shape's type by hand in the panel. |
| "Conversion failed", with a reason | Click Retry. If it fails again, contact us with the message. |
| A shape became the wrong type | Select it and change its type in the panel. |
| You can't find Resource in the type dropdown | Resource needs the Intermediate view or higher. Change it in Settings. |
| The panel doesn't match the diagram in draw.io | Choose Quodsi > Reload Model from Diagram. |
Signing in
- draw.io, nothing happens when you click Sign In. Sign-in opens in a separate window, so check whether your browser blocked a pop-up.
- draw.io, you can't find Sign In. It's in the Quodsi panel. Choose Quodsi > Show/Hide Quodsi Panel to show it.
- draw.io, Take the Tour is greyed out. It reads Take the Tour (after sign-in). Sign in first.
- Sign-in itself isn't working. Open Status and look at Signing in.
This version of Quodsi is out of date
You'll see this when your open copy of Quodsi is too old to talk to the service:
- In draw.io: "This version of Quodsi is out of date. Reload the page to get the latest version." Click Reload.
- In Lucidchart: "Quodsi has been updated. Reload LucidChart to get the latest version." Reload the Lucidchart tab.
Save your work before you reload.
Runs that don't start or don't finish
Each run shows its state: Queued, Running or finished. A failed run shows the reason beside it, and a Retry button.
| What you see | What to do |
|---|---|
| The last run failed. | Nothing more is known about the failure. Click Retry. If it fails again, contact us. |
| A failed run with a specific message | The model passed the panel's checks but the engine refused it. The message names what to fix, often a broken reference to a state or a resource requirement. Fix it and retry. |
| This model has validation errors — fix them before running. | Fix them as described under Reading validation messages. |
| Model sync failed — close and reopen Studies to retry. | Close the What-if Analysis window and open it again. Check you're still signed in. |
| Replications (150) exceeds the maximum of 100. | Lower the replications to 100 or fewer, including any scenario that changes them. See Plans and limits. |
| No results available for this scenario yet | The scenario hasn't finished a run. Run it, or wait for it to finish. |
| Simulation deadlocked | Entities each hold what another is waiting for, and nothing due can free them. The message names them and what each holds. Add a queue, or seize everything in one Requirement. See Resource. |
| A step couldn't change a state | A change failed during the run, usually a division by 0 or a number too big to hold. The message names the step, the state, the time and any expression. Guard an expression with an if, such as total / count if count > 0 else 0. |
| Run stopped: step visits with no time passing | Steps are looping, or creating entities, without taking any time, so the clock can't move. The message names a step on the loop. Give one of them a duration, or a way out. |
| Run stopped: a generator or activity went round with no time passing | A generator's inter-arrival time, or an activity's time between failures, keeps drawing zero, for example a Normal whose mean is far below zero. The message names it. Give it values above zero. |
| A run stays Queued or Running for a long time | Open Status and look at Running simulations. You can stop a run with Cancel run. |
| Results won't load | Open Status and look at Storing results. |
| Results look wrong | This usually isn't a fault. Check your time units first, then your warnings. See Check the model. |
Examples won't open
This affects draw.io, where examples are loaded from the internet.
- "Examples aren't available right now." Click Retry. Your network may be blocking the site the examples come from.
- "Showing the last saved list — couldn't refresh from GitHub." You're seeing the list from your last visit. The examples may still open.
- "These examples need a newer build. Please update Quodsi drawio." Reload the page.
Something broke on this page
Click the retry button or reload the page. Save your diagram first if you can. If it keeps happening, contact us.
Still stuck?
Email support@quodsi.com or visit the support page. It helps if you include the exact message and what you were doing. To copy your validation messages, click Copy to clipboard in the Validation panel. You can also reach us from Feedback & Support in the Quodsi menu.