Issue Summary

This ticket is created from CONFSERVER-93635 as a continuation as it shares similar behavior that still impacts Confluence after it is closed as fixed.

Confluence is throwing errors about "CSSErrorListener" while a user is being @ mentioned on a page comment.

Despite the error message, the notification will still manage to reach the recipient. However, since the error is thrown every time "NotificationSender" picks up a page, Confluence logs will get filled up with similar error messages quickly and create unnecessary noise.

This issue is not replicable on version 8.5.X

This is reproducible on Data Center: (yes)

Steps to Reproduce

1. Set up Confluence 8.6.1
2. Set up an SMTP mail server
3. @ mention a user on a Page Comment that would trigger an email notification
   • The page can even be a blank page, or simply a page with 1 line of text.

Expected Results

Confluence will not return any error about the user mention.

Actual Results

Confluence returns errors about "CSSErrorListener" on the user mention action that would trigger an email notification.

The below exception is thrown in the atlassian-confluence.log file:

2025-03-04 10:20:07,806 ERROR [NotificationSender:thread-1] [web.csskit.antlr4.CSSErrorListener] reportAttemptingFullContext CSSErrorListener full context | 
 -- url: /rest/tinymce/1/content/163926/comment | userName: admin | referer: http://localhost:8090/spaces/PROJ/pages/163926/Test+Page+One | traceId: ab3c9fe07d56f2cf
2025-03-04 10:20:07,807 ERROR [NotificationSender:thread-1] [web.csskit.antlr4.CSSErrorListener] reportAmbiguity CSSErrorListener ambiguity | 
 -- url: /rest/tinymce/1/content/163926/comment | userName: admin | referer: http://localhost:8090/spaces/PROJ/pages/163926/Test+Page+One | traceId: ab3c9fe07d56f2cf
2025-03-04 10:20:07,811 ERROR [NotificationSender:thread-1] [web.csskit.antlr4.CSSErrorListener] reportAttemptingFullContext CSSErrorListener full context | 
 -- url: /rest/tinymce/1/content/163926/comment | userName: admin | referer: http://localhost:8090/spaces/PROJ/pages/163926/Test+Page+One | traceId: ab3c9fe07d56f2cf
2025-03-04 10:20:07,814 ERROR [NotificationSender:thread-1] [web.csskit.antlr4.CSSErrorListener] reportAmbiguity CSSErrorListener ambiguity | 
 -- url: /rest/tinymce/1/content/163926/comment | userName: admin | referer: http://localhost:8090/spaces/PROJ/pages/163926/Test+Page+One | traceId: ab3c9fe07d56f2cf

Workaround

To suppress the error messages:
Via "Logging and Profiling"

1. Go to "Logging and Profiling" in the admin menu
2. Add "cz.vutbr.web" to the list via the text box under "Add New Entry"
3. Set logging level to "FATAL"
4. Click on "Add Entry"
5. Click "Save" (bottom of the "Logging and Profiling" page)
6. Refer Configuring Logging documentation for more details regarding logging configuration in Confluence

Via "log4j.properties" file

1. Open up the /confluence/WEB-INF/classes/log4j.properties file
2. Add the following line to the file:

   log4j.logger.cz.vutbr.web=FATAL 
   

3. Save the file
4. Apply the same changes to the rest of the nodes
5. Perform a rolling Confluence restart