ACS-AEM-Generic list- 500 Error thrown

[NitroHazeDev]

All,

Is there a limit to the number of items in an ACS Commons generic list . The page just appears blank and a 500 error is thrown. Limiting to 6 entries or 4 helps. Anyway i can get around the issue? I am on aem 6.5.8 

[Ravi_Pampana]

Hi,

I don't see any limitation , did you see any errors in logs? As per implementation it seems to be a straight forward of reading the values from a specific node. Can you check any if any of the special characters in the value is causing the issue.

[NitroHazeDev]

Totally, that is what makes me wonder, I see a Null pointer Exception but very unclear and version 4.10.0 acs commons. It does not appear to be special char issue
ERROR- GET /mnt/overlay/acs-commons/components/utilities/genericlist.html-    org.apache.sling.engine.impl.SlingRequestProcessorImpl service: Uncaught SlingException 

java.lang.NullPointerException: null
WARN - GET /mnt/overlay/acs-commons/components/utilities/genericlist.html- org.apache.sling.engine.impl.SlingHttpservletresponseImpl Response already committed. Failed to set status code from 200 to 500. 

Updated- I did set up debug logging and found out NPE at 
org.apache.sling.rewriter.impl.ProcessorConfigurationImpl.match(ProcessorConfigurationImpl.java:465)

at org.apache.sling.rewriter.impl.RewriterResponse.getProcessor(RewriterResponse.java:170) 
and more

I also tried reducing entries to 4 and it worked fine. I see people complain of this online 
https://github.com/Adobe-Consulting-Services/acs-aem-commons/issues/2503
https://stackoverflow.com/questions/68460284/aem-acs-commons-generic-list-editor-breaks-when-more-th...

However , i see nothing with rewriter config in logs .. unsure how i could debug further

[Ravi_Pampana]

I am able to replicate the issue when adding below below string to either title or value field

#!!@#$%^&*())_?><"L"'{

Getting below exception in logs

Caused by: java.lang.NullPointerException: null
25.04.2022 21:50:06.503 *ERROR* [[0:0:0:0:0:0:0:1] [1650948606483] GET /mnt/overlay/acs-commons/components/utilities/genericlist.html HTTP/1.1] org.apache.sling.engine.impl.SlingRequestProcessorImpl service: Uncaught SlingException

While checking acs-commons seems to be with below code

/apps/acs-commons/components/utilities/genericlist/list.json.jsp 

Not able to create json attribute correctly. 

[NitroHazeDev]

@Ravi_Pampana  The strange part is that i am able to work with the list successfully on my local but not on higher env. The .json (url exposed as JSON) works fine as well. It is the rendering of the list components on the page that throws a 500 Error. Will try checking for special characters but a simple, test1, test2 test3 upto say 15 entries breaks on higher env while it works fine on local.. so special characters does not seem like the cause.  Wondering if you happened to check the links i sent where people have spoken of generic list with more entries breaking? If there is a suggestion please let me know 

NPE occurs at this line

org.apache.sling.rewriter.impl.ProcessorConfigurationImpl.match(ProcessorConfigurationImpl.java:465)

[DEBAL_DAS]

I have tried with below combinations to replicate the issue-

1. Adobe Experience Manager 6.5.11.0 and acs-commons 5.2.0 as shown below -

Created a generic list with 21 entries but I didn't face the above issue -

2. Adobe Experience Manager 6.5.9.0 and acs-commons 4.10.0 as shown below -

Created a generic list with 15 entries but I didn't face the above issue -

But we faced this issue in our last project. I will keep you posted with AEM and acs common version.

[NitroHazeDev]

Hi @DEBAL_DAS 

Thank you for your help with this.

As mentioned this is not a problem on local instance as many have noted but on higher env .Please find the links shared for more details. Assumed Rewriter is the culprit, but that solved the issue momentarily. Attached logs

[DEBAL_DAS]

@NitroHazeDev ,

I haven't received reply yet on AEM and acs common version.

I can recall few things , we were using AEM 6.5.5 and initial acs commons version was 4.3.2

We took the decision to upgrade acs commons version then we faced this issue (page just appears blank , a 500 error is thrown and null pointer exception) after upgrade. We had these issues on QA and local instances as well.

After several trying we just reverted to previous acs commons version[4.3.2].

[DEBAL_DAS]

Hi @NitroHazeDev ,

I have got information we had the similar issue with AEM 6.5.4 and acs commons 4.5.X.

We tried with different approaches to fix the issue but nothing worked.

Then we reverted to acs commons 4.3.2. 

I know your are facing the issue on higher environment. Is it possible for you to install different acs commons version like 5.2.0 and validate the behavior.

[#10]

Hi @DEBAL_DAS, 

We've recently upgraded to acs commons 5.2.0 (AEM version 6.4.8.4) and I can confirm we're experiencing the same problem. I used a workaround found elsewhere online whereby I renamed a node "/apps/platform-configuration/config/rewriter," then tested and renamed it back to "rewriter." This fixed the problem in production (at least for now), but it unfortunately did not work for some lower environments. I'm still trying to track down what differences could be causing that, but hope the context is useful. 

Thank you!

[NitroHazeDev]

@DEBAL_DAS @Deleted Account  tried renaming and it did not work, infact knocking off the nodes did not help either. We had an in place upgrade not sure if that is the cause. Moving to lower version is a challenge at the moment. But glad to know that this is an issue and i can concur. I would most likely begin working towards a resolution, let's see if i can make it work
@Deleted Account  do let me know if you get to notice any differences, will keep you posted. 

[akashdeepAEM]

Hi @NitroHazeDev ,
cc @Ravi_Pampana @DEBAL_DAS 
Issue: acs commons generic lists with more than 8 items gives 500. 

I am able to reproduce the issue with latest acs-commons 5.3.2 on latest AEM 6.5.13 having /apps/<project>/config/rewriter.

As suggested, first tried removing rewriter node in /apps/<project>/config/rewriter helped. 
 https://stackoverflow.com/questions/68460284/aem-acs-commons-generic-list-editor-breaks-when-more-th...  

Fix: update node property order="-1" from its current value order="10" in /apps/<project>/config/rewriter/ as per the latest /libs/cq/config/rewriter/default order="-1" 
Note: 4.3.2 is a working version of acs-commons which supports classic and does not has this generic-lists issue. 
Hope it helps!

Thanks

[NitroHazeDev]

Hi @akashdeepAEM  , 4.3.2 may be the best, but compatibility wise there were issues with 6.5 , so we had to bump it up. We do not have any config/rewriter node to rename or temporarily delete. I hope this issue with varying fixes per acs version, where a solution works for one does not work for the other gets resolved at the root itself- i.e. ACS... I haven't had the time to debug it myself.

[ankita_das]

Hi @akashdeepAEM 

I am using AEM 6.5.9 (On-Prem) with ACS Commons 5.3.0 and facing the same issue.

I have a custom rewriter configuration with order 100. If I disable the rewriter or set the order to 1, Generic List works fine. However, this doesn't solve the issue as I need the custom Sling Transformer with an order greater than 1.

Downgrading is definitely not an option.

Not sure if this was ever addressed by the ACS Commons team. I went ahead and created an issue for the same: https://github.com/Adobe-Consulting-Services/acs-aem-commons/issues/2928.