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How to ask Canvas support to correct oauth_signature_base_string

Question asked by Kim Huang on Oct 15, 2019

Hi Folks,

I created a LTI tool provider and registered in Canvas of Princeton. It works until I have changed the launch link(I have accidentally had a typo in the launch link.). I found out the typo and tried to correct it by deleting the app(admin panel->settings->apps) and added it back with the correct launch link, but the oauth_signature_base_string still shows the wrong link as in red:  (The link with the typo just can't be correct.)



Error launch the photo roster: java.lang.Exception: net.oauth.OAuthProblemException: signature_invalid oauth_problem: signature_invalid oauth_signature: i+pybacEoBYR93/UAy4kQT6gxYU= oauth_signature_base_string: POST& 


Here is the xml to config this tool with the correct launch link. The correct launch link is in pink. 

<?xml version="1.0" encoding="UTF-8"?>
<cartridge_basiclti_link xmlns=""
    <blti:title>Class Photos</blti:title>
    <blti:description>Provides searchable students' photos of the class</blti:description>
    <blti:extensions platform="">
      <lticm:property name="privacy_level">public</lticm:property>
      <lticm:property name="domain"></lticm:property>
      <lticm:options name="course_navigation">
        <lticm:property name="visibility">admins</lticm:property>
        <lticm:property name="enabled">true</lticm:property>


For this kind of problem, who should I contact in 

Please help.