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

# Debug Template Errors

> Identify and fix Nextedy POWERSHEET server-rendered template failures by recognizing error markers, checking server logs, and applying systematic debugging techniques on Siemens Polarion ALM.

export const LastReviewed = ({date}) => {
  if (!date) return null;
  const formatted = new Date(`${date}T00:00:00Z`).toLocaleDateString("en-US", {
    year: "numeric",
    month: "long",
    day: "numeric",
    timeZone: "UTC"
  });
  return <p className="mt-10 text-sm text-gray-400 dark:text-zinc-500 not-prose">
      Last reviewed on {formatted}
    </p>;
};

## Prerequisites

* A powersheet document with server-rendered properties configured
* Access to Polarion server logs
* Familiarity with [Velocity template syntax](/powersheet/guides/server-rendering/use-velocity-template)

<Steps>
  <Step title="Recognize the Error Marker">
    When a Velocity template evaluation fails, Powersheet displays `#SERVER_RENDER_ERROR` in the affected cell instead of the computed value. This is a constant error marker that indicates a template configuration problem.

    <Frame>
      <img src="https://mintcdn.com/none-17b4493f/-WiVljKlDztH36bB/powersheet/diagrams/guides/server-rendering/debug-template-errors/diagram-1.svg?fit=max&auto=format&n=-WiVljKlDztH36bB&q=85&s=46ef0b825f77cf2f9293683958619d2d" alt="diagram" style={{ width: "500px", maxWidth: "100%" }} width="500" height="120" data-path="powersheet/diagrams/guides/server-rendering/debug-template-errors/diagram-1.svg" />
    </Frame>
  </Step>

  <Step title="Check Polarion Server Logs">
    The three most common exception types appear in the Polarion server logs when a template fails:

    | Exception Type            | Cause                             | Example                                 |
    | ------------------------- | --------------------------------- | --------------------------------------- |
    | ParseErrorException       | Invalid Velocity syntax           | Missing `#end`, unbalanced quotes       |
    | MethodInvocationException | Method call on null or wrong type | `$item.getTitle()` when `$item` is null |
    | ResourceNotFoundException | Referenced resource not found     | Missing include or macro                |

    Open the Polarion server log file and search for these exception names to find the exact error message and line number.
  </Step>

  <Step title="Validate Template Syntax">
    Common Velocity syntax errors that cause ParseErrorException:

    ```yaml theme={null}
    # WRONG: Missing #end
    serverRender: "#if($item.title)$item.title"

    # CORRECT: Properly closed block
    serverRender: "#if($item.title)$item.title#end"
    ```

    ```yaml theme={null}
    # WRONG: Unescaped special characters
    serverRender: "$item.title & $item.status"

    # CORRECT: Escaped or avoided
    serverRender: "$item.title and $item.status"
    ```

    <Warning title="Single-line templates">
      Server-rendered expressions are typically single-line strings in YAML. Multi-line Velocity logic must be compressed into one line or use Velocity's inline syntax.
    </Warning>
  </Step>

  <Step title="Add Null Checks">
    MethodInvocationException commonly occurs when accessing properties on null objects. Always guard against nulls:

    ```yaml theme={null}
    # WRONG: Assumes $module is always available
    serverRender: "$module.moduleName"

    # CORRECT: Null check first
    serverRender: "#if($module)$module.moduleName#else N/A#end"
    ```

    Key variables that can be null:

    * `$module` -- null when entity is not document-scoped
    * `$wi` -- null when entity is not a work item
    * Custom field values -- null when not set on the work item

    <Tip title="Defensive template pattern">
      Always wrap service calls and property access in `#if` checks: `#if($var && $var.method())$var.method()#else default#end`
    </Tip>
  </Step>

  <Step title="Test with Simple Expressions First">
    When debugging a complex template, simplify to isolate the problem:

    1. Replace your template with a constant: `serverRender: "test"` -- verify rendering works at all
    2. Add one variable: `serverRender: "$item.id"` -- verify context is available
    3. Add the failing expression piece by piece until the error reappears
  </Step>

  <Step title="Verify Property Configuration">
    Ensure the property hosting the server-rendered expression is correctly configured:

    ```yaml theme={null}
    properties:
      computedField:
        serverRender: "$item.title"
        readable: true      # Must be true to display
        updatable: false     # Always false for server-rendered
    ```

    <Info title="Verify in application">
      Some Polarion service methods may behave differently across versions. If a method call in your template causes errors, verify the method signature against your Polarion installation's API documentation.
    </Info>
  </Step>
</Steps>

## Common Error Patterns

| Symptom                         | Likely Cause                 | Fix                                       |
| ------------------------------- | ---------------------------- | ----------------------------------------- |
| All rows show error             | Template syntax error        | Check for missing `#end` or bad directive |
| Some rows show error            | Null data on specific items  | Add null checks for optional fields       |
| Error after Polarion upgrade    | API change in service method | Update method calls to new API            |
| Error on document entities only | `$wi` used on non-work-item  | Use `$item` instead or add type check     |

## Verify

After fixing template errors:

1. Open the powersheet document in Polarion
2. You should now see computed values in all cells that previously showed `#SERVER_RENDER_ERROR`
3. Test with work items that have empty or null fields to confirm null checks work
4. Verify that the Polarion server logs no longer show template-related exceptions

## See Also

* [Create a Computed Property](/powersheet/guides/server-rendering/create-computed-property) -- setting up server-rendered properties
* [Use Velocity Templates](/powersheet/guides/server-rendering/use-velocity-template) -- template syntax reference
* [Access Polarion Services](/powersheet/guides/server-rendering/access-polarion-services) -- platform service usage
* [Troubleshooting Guides](/powersheet/guides/troubleshooting/index) -- general troubleshooting resources

<LastReviewed date="2026-07-02" />