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Plugins Not Working gets 503 (Service Unavailable), in HAR log see "pool named |apex|pu|, is not able to proxy to the schema named APEX_PUBLIC_USER" (Doc ID 2744609.1)

Last updated on JANUARY 15, 2021

Applies to:

Oracle Application Express (APEX) - Version 20.1 and later
Information in this document applies to any platform.


On : APEX 20.1 version, Flow Builder

When attempting to use plugins,
the following error occurs.

Failed to load resource: the server responded with a status of 503 (Service Unavailable)
<plugin_name> is not defined

In an HAR result one can see:

Content-Type text/html
Error-Reason error="*APEX_PUBLIC_USER|apex|pu|"; error_description*=UTF-8''The database user for the connection pool named |apex|pu|, is not able to proxy to the schema named APEX_PUBLIC_USER. This could be a configured restriction on the maximum number of database sessions or an authorization failure.

The issue can be reproduced at will with the following steps:
1. Try to use application with plugins
2.Get the 503 error


 Installed a new packaged application


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