> ## Documentation Index
> Fetch the complete documentation index at: https://docs.glidepathcpm.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Common Errors and Warnings

> Troubleshooting errors and understanding warning messages

# Common Errors and Warnings

This guide explains common error messages and how to resolve them.

## Feature Spec Reference

**Module 3.7 — Circular Dependency Detection**\
**Various validation modules**

## Errors (Block Action)

### "Circular Dependency Detected"

* **Cause:** You tried to create a dependency that would create a loop (A→B→C→A)
* **Solution:** Remove or change one of the dependencies to break the loop
* **Example:** Task A depends on B, B depends on C, you try to make C depend on A—forbidden

### "Start Date Cannot Be Before Project Start"

* **Cause:** Task start date is earlier than project start date
* **Solution:** Adjust task start date to be on or after project start date

### "Target Completion Must Be After Start Date"

* **Cause:** In Create Project, target completion is before or same as start date
* **Solution:** Set target completion to a date after start date

### "Task Name Is Required"

* **Cause:** You tried to create a task without entering a name
* **Solution:** Enter a task name (1–200 characters)

### "Select at Least One Working Day"

* **Cause:** Work Week has no days checked
* **Solution:** Check at least one day (Mon–Fri recommended)

### "Duration Must Be Greater Than 0"

* **Cause:** Task duration was set to a negative or zero value (except milestones, which have duration 0)
* **Solution:** Enter a positive duration (e.g., 1, 2.5, 10)

## Warnings (Non-Blocking)

### "Task Has No Predecessors But Is Not ASAP"

* **Cause:** Task with constraint (e.g., FNLT) has no predecessor
* **Meaning:** Task may not schedule as expected
* **Action:** Consider changing to ASAP or adding a predecessor

### "Over-Constrained Task"

* **Cause:** Task has conflicting constraints or dependencies that can't be satisfied
* **Meaning:** CPM engine had to override one constraint to calculate a valid schedule
* **Action:** Review constraints and dependencies; remove one constraint if possible

### "Circular Constraint Warning"

* **Cause:** Constraint dates create an impossible situation
* **Example:** Start No Earlier Than Jan 15 + Finish No Earlier Than Jan 10 = impossible
* **Action:** Adjust constraint dates to be compatible

### "Resource Over-Allocated"

* **Cause:** Resource assigned to multiple overlapping tasks at >100% allocation
* **Meaning:** Resource can't be in two places at once
* **Action:** Shift one task later, add another resource, or reduce allocation %

### "Dependency Lag Exceeds Task Duration"

* **Cause:** Lag value is larger than the predecessor task duration
* **Example:** 5-day task with 10-day lag
* **Meaning:** Unusual but not always wrong (intentional delay)
* **Action:** Verify this is intentional; consider reducing lag

## Validation Rules

| Rule                         | Triggers                        | Resolution                                       |
| ---------------------------- | ------------------------------- | ------------------------------------------------ |
| **Required Name**            | Empty task name                 | Enter a task name                                |
| **Valid Date**               | Invalid date format             | Use MM/DD/YYYY (US) or DD/MM/YYYY (EU) format    |
| **Valid Duration**           | Duration = 0 (except milestone) | Milestones only; regular tasks need duration > 0 |
| **No Circular Deps**         | A→B→C→A dependency              | Remove one dependency link                       |
| **Constraint Date Validity** | Constraint date before start    | Adjust constraint date to be compatible          |

***

## Next Steps

* [Performance Tips](/reference/02-performance-tips)
* [FAQ](/reference/04-faq)