P: I am unable to create a Slideshow.

After looking at the log file that David sent me privately, I am able to help David resolve his issue.

Resolution:
Make sure that you have read/write access to this directory on your system

Windows: \Users\your account name\AppData\Local\Adobe/Lightroom\Caches\velo\
MacOS: /Users/your account name/Library/Caches/Adobe/Lightroom/velo

Or you can simply try to delete the folder altogether.

Hi David, I sent you a private message to request the info.

Hi Simon

I followed the instructions here:-

https://forums.adobe.com/thread/925598

Do you want me to repeat it?

Hi David, did you generate the traceback while you are reproducing the "An internal error has occurred: ?:0: attempto index a nil value" error?

Hi Smit

Did you get the files I put on Dropbox?

Hi Simon - any response to the log?

Is this ok?

00000001 0.00000000 [5592] 8048 0000000000000000 ENTER: DllCanUnloadNow 
00000002 4.04362345 [5592] 11468 0000000000000000 ENTER: DllCanUnloadNow 
00000003 5.19718409 [17888] AgMessageProcessor :: request DEBUG sending observable request( userdata: 0000000022321D28, "setProxyCredentials", "", "" ) 
00000004 5.19721365 [17888]   
00000005 6.37562180 [17888] fjkhdfjhdfjk 
00000006 6.37860632 [17888] WPD Service responding. 
00000007 7.82348013 [17888] L:  
00000008 7.82351494 [17888] maybeAssignLayoutAttributeL had an unhandled key: margin_right 
00000009 7.82353973 [17888]   
00000010 14.36055946 [17888] AgMessageProcessor :: request DEBUG sending observable request( userdata: 000000002BF106C8, "get", "https://api-lr.adbecrsl.com/v1.0/catalogs?subtype=lightroom%3BX-lightroom";, nil ) 
00000011 14.36059761 [17888]   
00000012 16.91984558 [17888] AgMessageProcessor :: request DEBUG AgMessageProcessor :: request DEBUG DISPOSING observable request( %s, %s, %s, %s ) via %s   userdata: 000000002BF106C8   get   https://api-lr.adbecrsl.com/v1.0/catalogs?subtype=lightroom%3BX-lightroom   nil   :traceback: 
00000013 16.91989708 [17888]   
00000014 53.62569046 [5592] 19352 0000000000000000 ENTER: DllCanUnloadNow 
00000015 55.37115479 [18156] ShellStreams: Attach 
00000016 55.37128067 [18156] ShellStreams: Initialized 
00000017 55.37215042 [18156] Resource DLL loaded at path C:\Program Files (x86)\Common Files\Apple\Internet Services\ShellStreams.resources\en_GB.lproj\ShellStreamsLocalized.dll 
00000018 55.37216949 [18156] Not running under explorer. Will not set thread locale 
00000019 55.56342316 [18156] 16668 03EF5C58 ENTER: ShellStreamsFolder::ShellStreamsFolder 
00000020 55.56361389 [18156] pidl = 1f50e04fd020ea3a6910a2d8802b30309d140 -> 2e80853fd6f0ec379740b3d61b4a891711800 ->  
00000021 55.56367493 [18156]  
00000022 55.56373596 [18156] 16668 03EF5C58 ENTER: ShellStreamsFolder::CreateViewObject 
00000023 56.35900879 [18156] 16668 0447CB38 ENTER: ShellStreamsFolder::ShellStreamsFolder 
00000024 56.35914230 [18156] pidl = 1f50e04fd020ea3a6910a2d8802b30309d140 -> 2e80853fd6f0ec379740b3d61b4a891711800 ->  
00000025 56.35919189 [18156]  
00000026 56.35925674 [18156] 16668 0447CB38 ENTER: ShellStreamsFolder::CreateViewObject 
00000027 56.38678741 [18156] ShellStreams: Detach 

It would be helpful to collect a traceback log to determine where the error is coming from. Instructions https://forums.adobe.com/thread/925598.

Hi Smit

Thanks for response. As my earlier note states I have tried different image selections and different catalogs. Will put catalog and files into Dropbox and send you the link.