Unable to load Power-Up



I'm creating a very simple Power-Up which should add a button to the board.

I followed the Power-Up tutorial on Trello and created the necessary files over https and added the Power-Up in the admin section.

When I go to any board and try to activate the Power-Up, I can see it in the list, but with an error message "Unable to load Power-Up"

My question is : "is there any way to debug this ?"

Otherwise could anyone have a look to my files and tell me if something looks wrong ?

Thanks in advance for your help


1 answer

1 accepted

0 votes
Oscar Triscon Community Champion Jul 21, 2017

Looks like your server doesn't set the Access-Control-Allow-Origin header. See https://developer.mozilla.org/en-US/docs/Web/HTTP/Access_control_CORS

You need to add the header to allow trello.com to load your powerup from an scripting request.

Thanks Oscar.

I added the header but this still does not work.

I've imported the Trello Power-up template code on my server and it still does not work, which shows that the server is the issue.

Specially seeing that if I import the same manijest.json file from github it works fine.

I've checked both servers HTTP headers but I don't manage to find where this could come from.

Do you have any idea ?



Status: HTTP/1.1 200 OK
Date: Sat, 22 Jul 2017 09:46:51 GMT  
Server: Apache  
Last-Modified: Sat, 22 Jul 2017 09:38:29 GMT  
ETag: "c0cf1a33-298-554e4be8f8c63"  
Accept-Ranges: bytes  
Vary: Accept-Encoding  
Content-Encoding: gzip  
Access-Control-Allow-Origin: *  
Content-Length: 365  
Connection: close  
Content-Type: application/json; charset=utf-8  
Strict-Transport-Security: max-age=16000000; includeSubDomains; preload


Oscar Triscon Community Champion Jul 22, 2017

Try adding these three header lines:

Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET, HEAD
Access-Control-Max-Age: 3000


Thanks, it worked pefectly !


Thanks again for your help


i face the same problem.

Where to add this script?


I created an .htaccess file as follow in the powerup folder


<IfModule mod_headers.c>
Header set Access-Control-Allow-Origin "*"
Header set Access-Control-Allow-Methods "GET, HEAD"
Header set Access-Control-Max-Age "3000"

Suggest an answer

Log in or Join to answer
Community showcase
Bridget Sauer
Published Feb 02, 2018 in Trello

Atlassian User Groups: Trello edition

You’re invited to our first ever Trello User Groups   Good news for current and aspiring Trello enthusiasts! We’re launching Trello User Groups so that you can network, share ideas, solve ...

1,116 views 7 10
Read article

Atlassian User Groups

Connect with like-minded Atlassian users at free events near you!

Find a group

Connect with like-minded Atlassian users at free events near you!

Find my local user group

Unfortunately there are no AUG chapters near you at the moment.

Start an AUG

You're one step closer to meeting fellow Atlassian users at your local meet up. Learn more about AUGs

Groups near you
Atlassian Team Tour

Join us on the Team Tour

We're bringing product updates and pro tips on teamwork to ten cities around the world.

Save your spot