<p dir="auto"><strong>Apache Airflow version</strong>:</p>
<p dir="auto"><strong>Kubernetes version (if you are using kubernetes)</strong> (use <code class="notranslate">kubectl version</code>): 1.18+</p>
<p dir="auto"><strong>Environment</strong>:</p>
<ul dir="auto">
<li><strong>Cloud provider or hardware configuration</strong>: GCP</li>
<li><strong>OS</strong> (e.g. from /etc/os-release):</li>
<li><strong>Kernel</strong> (e.g. <code class="notranslate">uname -a</code>):</li>
<li><strong>Install tools</strong>:</li>
<li><strong>Others</strong>:</li>
</ul>
<p dir="auto"><strong>What happened</strong>:<br>
Tried to trigger a dag with config but got an error saying "Invalid JSON configuration, must be a dict"<br>
This worked in 2.1.0<br>
<a target="_blank" rel="noopener noreferrer nofollow" href="https://user-images.githubusercontent.com/8545525/125070083-eaed7680-e0b7-11eb-954b-c3e149a98bd8.png"><img src="https://user-images.githubusercontent.com/8545525/125070083-eaed7680-e0b7-11eb-954b-c3e149a98bd8.png" alt="image" style="max-width: 100%;"></a></p>

<p dir="auto"><strong>What you expected to happen</strong>:</p>

<p dir="auto"><strong>How to reproduce it</strong>:<br>
Running airflow 2.1.1 try trigger a dag with config</p>
<p dir="auto"><strong>Anything else we need to know</strong>:<br>
How often does this problem occur? Once? Every time etc?<br>
Always<br>
Any relevant logs to include? Put them here in side a detail tag:</p>
<details><summary>webserver_logs</summary>
```
10.60.7.19 - - [09/Jul/2021:10:00:46 +0000] "POST /trigger?dag_id={dag_id}&amp;origin=%2Ftree%3Fdag_id%3D{dag_id}HTTP/1.1" 200 19096 "https://{airflow-domain}/trigger?dag_id={dag_id}&amp;origin=%2Ftree%3Fdag_id%3D{dag_id}" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.114 Safari/537.36"
10.60.7.19 - - [09/Jul/2021:10:00:46 +0000] "GET /static/dist/lint.css HTTP/1.1" 304 0 "https://{airflow-domain}/trigger?dag_id={dag_id}&amp;origin=%2Ftree%3Fdag_id%3D{dag_id}" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.114 Safari/537.36"
10.60.7.19 - - [09/Jul/2021:10:00:46 +0000] "GET /static/dist/codemirror.css HTTP/1.1" 304 0 "https://{airflow-domain}/trigger?dag_id={dag_id}&amp;origin=%2Ftree%3Fdag_id%3D{dag_id}" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.114 Safari/537.36"
```
</details>
<p dir="auto"><strong>Apache Airflow version</strong>: 2.1.1</p>
<p dir="auto"><strong>Kubernetes version (if you are using kubernetes)</strong> (use <code class="notranslate">kubectl version</code>): NO</p>
<p dir="auto"><strong>Environment</strong>: local (docker + ubuntu)</p>
<ul dir="auto">
<li><strong>Cloud provider or hardware configuration</strong>:</li>
<li><strong>OS</strong> (e.g. from /etc/os-release): Debian GNU/Linux 10 (buster)</li>
<li><strong>Kernel</strong> (e.g. <code class="notranslate">uname -a</code>):  linux</li>
</ul>
<p dir="auto"><strong>What happened</strong>:<br>
airflow is not accepting configuration from Admin UI</p>
<p dir="auto">when I submit a DAG configuration from UI, it is giving me error <code class="notranslate">Invalid JSON configuration, must be a dict</code></p>
<p dir="auto"><a target="_blank" rel="noopener noreferrer nofollow" href="https://user-images.githubusercontent.com/1611331/124464058-56320280-ddb1-11eb-9cba-4656263761ba.png"><img src="https://user-images.githubusercontent.com/1611331/124464058-56320280-ddb1-11eb-9cba-4656263761ba.png" alt="image" style="max-width: 100%;"></a></p>
<p dir="auto">the same workflow is working in airflow 2.1.0 version<br>
I think this issue occurred in this PR <a class="issue-link js-issue-link" data-error-text="Failed to load title" data-id="842710273" data-permission-text="Title is private" data-url="https://github.com/apache/airflow/issues/15057" data-hovercard-type="pull_request" data-hovercard-url="/apache/airflow/pull/15057/hovercard" href="https://github.com/apache/airflow/pull/15057">#15057</a></p>
<p dir="auto"><strong>What you expected to happen</strong>:<br>
Airflow admin should accept the conf from UI and trigger the dag</p>
<p dir="auto"><strong>How to reproduce it</strong>:<br>
It can be reproduced for all cases, we have to put any valid JSON into the configuration window on a DAG</p>
<p dir="auto"><strong>Willing to submit PR</strong><br>
YES</p>