<p>The issue has to do with another third party plugin (<a href="https://github.com/objectivehtml/Postmaster-for-Craft-CMS" rel="nofollow noreferrer">Postmaster</a>) installed and also using <a href="http://carbon.nesbot.com" rel="nofollow noreferrer">Carbon</a>. The Postmaster plugin appears to be using an older copy of Carbon and Calendar is loading Postmaster's Carbon library, causing issues.</p>

<p>Manually updating the <strong>vendors</strong> directory to use latest versions may resolve this issue. We will try to reach out to the developer of Postmaster and see if they can resolve this on their end. :)</p>

<p>Customers effected with this issue can contact <a href="https://solspace.com/craft/create-ticket/calendar" rel="nofollow noreferrer">Solspace support</a> for an updated <strong>vendors</strong> folder for Postmaster that may resolve the issue.</p>

CC BY-SA 3.0
2016-12-13T04:02:17.803Z
2016-12-13T04:02:17.803Z
Solspace
<p>I've got Solspace Calendar installed to the best of my knowledge. I have repurposed the 'calendar_demo' files to 'calendar'. Both /calendar and /calendar_demo just show:</p>

<blockquote>
  <p>"Call to undefined method Calendar\Library\Carbon::setWeekStartsAt()" in DateHelper.php.</p>
</blockquote>

<p>/calendar/week does the same. A path like calendar/2016/11 just give a Twig error.</p>

<p>I can't understand why this is happening. I'll give more details if you ask me, I don't know what else to give.</p>

CC BY-SA 3.0
2016-11-09T18:54:27.180Z
Have you tried contacting Solspace on the chance it's a bug?
Brad Bell
CC BY-SA 3.0
2016-11-10T07:10:45.650Z
Just to clarify, does this error happen when you use the demo templates (without modifying templates, paths, etc)?
Solspace
CC BY-SA 3.0
2016-11-16T19:57:36.280Z
@solspace. Yes, that is correct.
Lynsey Gwin
CC BY-SA 3.0
2016-11-16T19:58:31.737Z
I happens on my local and dev environments.
Lynsey Gwin
<plugin-solspacecalendar>
"Call to undefined method Calendar\Library\Carbon::setWeekStartsAt()" Solspace Calendar
# "Call to undefined method Calendar\Library\Carbon::setWeekStartsAt()" Solspace Calendar

(Asked by: username_0 on 2016-11-09)

I've got username_2 Calendar installed to the best of my knowledge. I have repurposed the 'calendar\_demo' files to 'calendar'. Both /calendar and /calendar\_demo just show:

> "Call to undefined method Calendar\Library\Carbon::setWeekStartsAt()" in DateHelper.php.

/calendar/week does the same. A path like calendar/2016/11 just give a Twig error.

I can't understand why this is happening. I'll give more details if you ask me, I don't know what else to give.

**Tags:** plugin-solspacecalendar

> **Comments:**
> **username_1**: Have you tried contacting username_2 on the chance it's a bug?  
> **username_2**: Just to clarify, does this error happen when you use the demo templates (without modifying templates, paths, etc)?  
> **username_0**: @solspace. Yes, that is correct.  
> **username_0**: I happens on my local and dev environments.  

---

## 1 answers

### Answer by username_2 on 2016-12-13. Score: 1

The issue has to do with another third party plugin ([Postmaster](https://github.com/objectivehtml/Postmaster-for-Craft-CMS)) installed and also using [Carbon](http://carbon.nesbot.com). The Postmaster plugin appears to be using an older copy of Carbon and Calendar is loading Postmaster's Carbon library, causing issues.

Manually updating the **vendors** directory to use latest versions may resolve this issue. We will try to reach out to the developer of Postmaster and see if they can resolve this on their end. :)

Customers effected with this issue can contact [username_2 support](https://solspace.com/craft/create-ticket/calendar) for an updated **vendors** folder for Postmaster that may resolve the issue.


---

