Confluence stopped creating thumbnails for uploaded PDF/PPTX files

[Gerald Schneider]

Recently one of our three Confluence instances stopped generating thumbnails for uploaded pdf files.

Excerpt from the log:

2024-05-07 09:51:57,062 INFO [http-nio-8090-exec-11] [synchrony.service.http.SynchronyRequestExecutor] execute Initiating request PUT http://127.0.0.1:8091/synchrony/v1/data/Example-3b6ece80-5d0e-31f3-ab38-f11704b0163a/confluence-50331658?state-at=@head&state-format=html HTTP/1.1 for 50331658
2024-05-07 09:52:09,637 WARN [http-nio-8090-exec-17] [internal.content.collab.ReconcileReferringContentTask] getShouldIncludeOwnContent Could not find shouldIncludeOwnContentMap for Content ID 84646070 but will reconcile anyway
-- url: /confluence/plugins/drag-and-drop/upload.action | userName: gerald | action: upload | referer: https://host.example.com/confluence/pages/resumedraft.action?draftId=84646070&draftShareId=dfeae20b-393a-423f-aa08-400c195dcc52& | traceId: 22532f09db822c0c
2024-05-07 09:52:09,644 WARN [document-conversion-sandbox-launcher-2] [impl.util.sandbox.SandboxProcess] startIfDead Sandbox 0 has died
-- url: /confluence/rest/documentConversion/latest/conversion/thumbnail/results | userName: gerald | referer: https://host.example.com/confluence/pages/resumedraft.action?draftId=84646070&draftShareId=dfeae20b-393a-423f-aa08-400c195dcc52& | traceId: eda882a0f99a205d
2024-05-07 09:52:09,644 INFO [http-nio-8090-exec-17] [synchrony.service.http.SynchronyRequestExecutor] execute Initiating request PUT http://127.0.0.1:8091/synchrony/v1/data/Example-3b6ece80-5d0e-31f3-ab38-f11704b0163a/confluence-50331658?state-at=@head&state-format=html HTTP/1.1 for 50331658
2024-05-07 09:52:09,645 WARN [document-conversion-sandbox-launcher-2] [impl.util.sandbox.SandboxProcess] startIfDead Attempting to restart the sandbox 0
-- url: /confluence/rest/documentConversion/latest/conversion/thumbnail/results | userName: gerald | referer: https://host.example.com/confluence/pages/resumedraft.action?draftId=84646070&draftShareId=dfeae20b-393a-423f-aa08-400c195dcc52& | traceId: eda882a0f99a205d
2024-05-07 09:52:12,410 INFO [http-nio-8090-exec-2] [synchrony.service.http.SynchronyRequestExecutor] execute Initiating request PUT http://127.0.0.1:8091/synchrony/v1/data/Example-3b6ece80-5d0e-31f3-ab38-f11704b0163a/confluence-50331658?state-at=@head&state-format=html HTTP/1.1 for 50331658
2024-05-07 09:53:11,444 WARN [Caesium-1-4] [impl.schedule.caesium.JobRunnerWrapper] runJob Scheduled job com.balsamiq.scheduler.JobRunner_BAS_Gardening#com.balsamiq.confluence.plugins.mockups.Scheduler_2 failed with response JobRunnerResponse[runOutcome=FAILED,message='doYourStuffHere failed: service proxy has been destroyed']
2024-05-07 09:54:11,994 WARN [sandbox-terminator] [impl.util.sandbox.SandboxLocalProcessPool] lambda$startTerminator$0 Request has taken 122349ms exceeds l
imit 120000ms terminating sandbox
-- url: /confluence/plugins/drag-and-drop/upload.action | userName: gerald | action: upload | referer: https://host.example.com/confluence/pag
es/resumedraft.action?draftId=84646070&draftShareId=dfeae20b-393a-423f-aa08-400c195dcc52& | traceId: 0620767445f8d8c4
2024-05-07 09:54:12,012 WARN [document-conversion-sandbox-launcher-3] [impl.util.sandbox.SandboxProcess] startIfDead Sandbox 0 has died
-- url: /confluence/rest/documentConversion/latest/conversion/thumbnail/results | userName: gerald | referer: https://host.example.com/conflue
nce/pages/resumedraft.action?draftId=84646070&draftShareId=dfeae20b-393a-423f-aa08-400c195dcc52& | traceId: 192e9486318c337d
2024-05-07 09:54:12,013 WARN [document-conversion-sandbox-launcher-3] [impl.util.sandbox.SandboxProcess] startIfDead Attempting to restart the sandbox 0
-- url: /confluence/rest/documentConversion/latest/conversion/thumbnail/results | userName: gerald | referer: https://host.example.com/conflue
nce/pages/resumedraft.action?draftId=84646070&draftShareId=dfeae20b-393a-423f-aa08-400c195dcc52& | traceId: 192e9486318c337d
2024-05-07 09:54:12,013 WARN [sandbox-terminator] [impl.util.sandbox.SandboxLocalProcessPool] lambda$startTerminator$0 Request has taken 121104ms exceeds l
imit 120000ms terminating sandbox
-- url: /confluence/plugins/drag-and-drop/upload.action | userName: gerald | action: upload | referer: https://host.example.com/confluence/pag
es/resumedraft.action?draftId=84646070&draftShareId=dfeae20b-393a-423f-aa08-400c195dcc52& | traceId: 0620767445f8d8c4
2024-05-07 09:54:12,015 WARN [ForkJoinPool.commonPool-worker-3] [plugins.conversion.impl.LocalFileSystemConversionResultSupplier] lambda$performConversionI
nSandbox$2 Error when performing conversion com.atlassian.confluence.plugins.conversion.impl.LocalFileSystemConversionResultSupplier$3@660eb825[attachment=
/download/attachments/50331658/2024-04-18%20Report%20SC.pdf?version=1&modificationDate=1715068329507&api=v2,conversionType=THUMBNAIL] in the sandbox
java.util.concurrent.CompletionException: com.atlassian.confluence.util.sandbox.SandboxTimeoutException: Sandbox request has been killed because it exceede
d time limit of 120 seconds
at java.base/java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:315)
at java.base/java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:320)
at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1770)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
at java.base/java.lang.Thread.run(Thread.java:840)
Caused by: com.atlassian.confluence.util.sandbox.SandboxTimeoutException: Sandbox request has been killed because it exceeded time limit of 120 seconds
at com.atlassian.confluence.impl.util.sandbox.SandboxProcess.tryToThrowSpecificException(SandboxProcess.java:171)
at com.atlassian.confluence.impl.util.sandbox.SandboxProcess.execute(SandboxProcess.java:139)
at com.atlassian.confluence.impl.util.sandbox.SandboxLocalProcessPool.execute(SandboxLocalProcessPool.java:107)
at com.atlassian.confluence.impl.util.sandbox.ConfluenceSandboxPoolFactory$LazySandbox.execute(ConfluenceSandboxPoolFactory.java:70)
at com.atlassian.confluence.impl.util.sandbox.DefaultSandbox.execute(DefaultSandbox.java:41)
at com.atlassian.confluence.plugins.conversion.impl.sandbox.LocalDocumentConversionSandbox.execute(LocalDocumentConversionSandbox.java:66)
at com.atlassian.confluence.plugins.conversion.impl.sandbox.LocalDocumentConversionSandbox.execute(LocalDocumentConversionSandbox.java:59)
at com.atlassian.confluence.plugins.conversion.impl.sandbox.DelegatingDocumentConversionSandbox.execute(DelegatingDocumentConversionSandbox.java:47)
at com.atlassian.confluence.plugins.conversion.impl.LocalFileSystemConversionResultSupplier.lambda$performConversionInSandbox$1(LocalFileSystemConversionResultSupplier.java:227)
at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1768)
... 3 more
Caused by: java.io.EOFException: error deserialize sandbox message
at com.atlassian.confluence.impl.util.sandbox.SandboxMessage.receiveMessage(SandboxMessage.java:50)
at com.atlassian.confluence.impl.util.sandbox.SandboxProcess.receiveMessage(SandboxProcess.java:227)
at com.atlassian.confluence.impl.util.sandbox.SandboxProcess.execute(SandboxProcess.java:136)
... 11 more
2024-05-07 09:54:12,023 WARN [ForkJoinPool.commonPool-worker-3] [plugins.conversion.impl.FileSystemConversionState] markAsError Creating error file: /var/atlassian/application-data/confluence/shared-home/dcl-thumbnail/158/81/50331658/352944134_1.err
2024-05-07 09:54:12,036 WARN [document-conversion-sandbox-launcher-2] [impl.util.sandbox.SandboxProcess] startIfDead Sandbox 1 has died
-- url: /confluence/rest/documentConversion/latest/conversion/thumbnail/results | userName: gerald | referer: https://host.example.com/confluence/pages/resumedraft.action?draftId=84646070&draftShareId=dfeae20b-393a-423f-aa08-400c195dcc52& | traceId: eda882a0f99a205d
2024-05-07 09:54:12,036 WARN [document-conversion-sandbox-launcher-2] [impl.util.sandbox.SandboxProcess] startIfDead Attempting to restart the sandbox 1
-- url: /confluence/rest/documentConversion/latest/conversion/thumbnail/results | userName: gerald | referer: https://host.example.com/confluence/pages/resumedraft.action?draftId=84646070&draftShareId=dfeae20b-393a-423f-aa08-400c195dcc52& | traceId: eda882a0f99a205d
2024-05-07 09:54:12,038 WARN [ForkJoinPool.commonPool-worker-3] [plugins.conversion.impl.LocalFileSystemConversionResultSupplier] lambda$performConversionInSandbox$2 Error when performing conversion com.atlassian.confluence.plugins.conversion.impl.LocalFileSystemConversionResultSupplier$3@16de519a[attachment=/download/attachments/50331658/2024-04-18%20Report%20SC.pdf?version=1&modificationDate=1715068329507&api=v2,conversionType=THUMBNAIL] in the sandbox
java.util.concurrent.CompletionException: com.atlassian.confluence.util.sandbox.SandboxTimeoutException: Sandbox request has been killed because it exceeded time limit of 120 seconds
at java.base/java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:315)
at java.base/java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:320)
at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1770)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
at java.base/java.lang.Thread.run(Thread.java:840)
Caused by: com.atlassian.confluence.util.sandbox.SandboxTimeoutException: Sandbox request has been killed because it exceeded time limit of 120 seconds
at com.atlassian.confluence.impl.util.sandbox.SandboxProcess.tryToThrowSpecificException(SandboxProcess.java:171)
at com.atlassian.confluence.impl.util.sandbox.SandboxProcess.execute(SandboxProcess.java:139)
at com.atlassian.confluence.impl.util.sandbox.SandboxLocalProcessPool.execute(SandboxLocalProcessPool.java:107)
at com.atlassian.confluence.impl.util.sandbox.ConfluenceSandboxPoolFactory$LazySandbox.execute(ConfluenceSandboxPoolFactory.java:70)
at com.atlassian.confluence.impl.util.sandbox.DefaultSandbox.execute(DefaultSandbox.java:41)
at com.atlassian.confluence.plugins.conversion.impl.sandbox.LocalDocumentConversionSandbox.execute(LocalDocumentConversionSandbox.java:66)
at com.atlassian.confluence.plugins.conversion.impl.sandbox.LocalDocumentConversionSandbox.execute(LocalDocumentConversionSandbox.java:59)
at com.atlassian.confluence.plugins.conversion.impl.sandbox.DelegatingDocumentConversionSandbox.execute(DelegatingDocumentConversionSandbox.java:47)
at com.atlassian.confluence.plugins.conversion.impl.LocalFileSystemConversionResultSupplier.lambda$performConversionInSandbox$1(LocalFileSystemConversionResultSupplier.java:227)
at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1768)
... 3 more
Caused by: java.io.EOFException: error deserialize sandbox message
at com.atlassian.confluence.impl.util.sandbox.SandboxMessage.receiveMessage(SandboxMessage.java:50)
at com.atlassian.confluence.impl.util.sandbox.SandboxProcess.receiveMessage(SandboxProcess.java:227)
at com.atlassian.confluence.impl.util.sandbox.SandboxProcess.execute(SandboxProcess.java:136)
... 11 more
2024-05-07 09:54:12,038 WARN [ForkJoinPool.commonPool-worker-3] [plugins.conversion.impl.FileSystemConversionState] markAsError Creating error file: /var/atlassian/application-data/confluence/shared-home/dcl-thumbnail/158/81/50331658/352944134_1.err
2024-05-07 09:54:15,037 WARN [sandbox-terminator] [impl.util.sandbox.SandboxLocalProcessPool] lambda$startTerminator$0 Request has taken 123143ms exceeds limit 120000ms terminating sandbox
-- url: /confluence/plugins/drag-and-drop/upload.action | userName: gerald | action: upload | referer: https://host.example.com/confluence/pages/resumedraft.action?draftId=84646070&draftShareId=dfeae20b-393a-423f-aa08-400c195dcc52& | traceId: 0620767445f8d8c4
2024-05-07 09:54:15,055 WARN [document-conversion-sandbox-launcher-4] [impl.util.sandbox.SandboxProcess] startIfDead Sandbox 0 has died
-- url: /confluence/rest/api/content/50331658 | userName: gerald | referer: https://host.example.com/confluence/pages/resumedraft.action?draftId=84646070&draftShareId=dfeae20b-393a-423f-aa08-400c195dcc52& | traceId: 54efb0e50b050e75
2024-05-07 09:54:15,055 WARN [document-conversion-sandbox-launcher-4] [impl.util.sandbox.SandboxProcess] startIfDead Attempting to restart the sandbox 0
-- url: /confluence/rest/api/content/50331658 | userName: gerald | referer: https://host.example.com/confluence/pages/resumedraft.action?draftId=84646070&draftShareId=dfeae20b-393a-423f-aa08-400c195dcc52& | traceId: 54efb0e50b050e75
2024-05-07 09:54:15,061 WARN [ForkJoinPool.commonPool-worker-3] [plugins.conversion.impl.LocalFileSystemConversionResultSupplier] lambda$performConversionInSandbox$2 Error when performing conversion com.atlassian.confluence.plugins.conversion.impl.LocalFileSystemConversionResultSupplier$3@36491c8f[attachment=/download/attachments/50331658/2024-04-18%20Report%20SC.pdf?version=1&modificationDate=1715068329507&api=v2,conversionType=THUMBNAIL] in the sandbox
java.util.concurrent.CompletionException: com.atlassian.confluence.util.sandbox.SandboxTimeoutException: Sandbox request has been killed because it exceeded time limit of 120 seconds
at java.base/java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:315)
at java.base/java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:320)
at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1770)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
at java.base/java.lang.Thread.run(Thread.java:840)
Caused by: com.atlassian.confluence.util.sandbox.SandboxTimeoutException: Sandbox request has been killed because it exceeded time limit of 120 seconds
at com.atlassian.confluence.impl.util.sandbox.SandboxProcess.tryToThrowSpecificException(SandboxProcess.java:171)
at com.atlassian.confluence.impl.util.sandbox.SandboxProcess.execute(SandboxProcess.java:139)
at com.atlassian.confluence.impl.util.sandbox.SandboxLocalProcessPool.execute(SandboxLocalProcessPool.java:107)
at com.atlassian.confluence.impl.util.sandbox.ConfluenceSandboxPoolFactory$LazySandbox.execute(ConfluenceSandboxPoolFactory.java:70)
at com.atlassian.confluence.impl.util.sandbox.DefaultSandbox.execute(DefaultSandbox.java:41)
at com.atlassian.confluence.plugins.conversion.impl.sandbox.LocalDocumentConversionSandbox.execute(LocalDocumentConversionSandbox.java:66)
at com.atlassian.confluence.plugins.conversion.impl.sandbox.LocalDocumentConversionSandbox.execute(LocalDocumentConversionSandbox.java:59)
at com.atlassian.confluence.plugins.conversion.impl.sandbox.DelegatingDocumentConversionSandbox.execute(DelegatingDocumentConversionSandbox.java:47)
at com.atlassian.confluence.plugins.conversion.impl.LocalFileSystemConversionResultSupplier.lambda$performConversionInSandbox$1(LocalFileSystemConversionResultSupplier.java:227)
at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1768)
... 3 more
Caused by: java.io.IOException: Stream closed
at java.base/java.io.BufferedInputStream.getBufIfOpen(BufferedInputStream.java:168)
at java.base/java.io.BufferedInputStream.fill(BufferedInputStream.java:212)
at java.base/java.io.BufferedInputStream.read(BufferedInputStream.java:263)
at java.base/java.io.DataInputStream.readInt(DataInputStream.java:382)
at com.atlassian.confluence.impl.util.sandbox.SandboxMessage.receiveMessage(SandboxMessage.java:43)
at com.atlassian.confluence.impl.util.sandbox.SandboxProcess.receiveMessage(SandboxProcess.java:227)
at com.atlassian.confluence.impl.util.sandbox.SandboxProcess.execute(SandboxProcess.java:136)
... 11 more
2024-05-07 09:54:15,061 WARN [ForkJoinPool.commonPool-worker-3] [plugins.conversion.impl.FileSystemConversionState] markAsError Creating error file: /var/atlassian/application-data/confluence/shared-home/dcl-thumbnail/158/81/50331658/352944134_1.err
2024-05-07 09:54:28,038 WARN [sandbox-terminator] [impl.util.sandbox.SandboxLocalProcessPool] lambda$startTerminator$0 Request has taken 137445ms exceeds limit 120000ms terminating sandbox
-- url: /confluence/plugins/drag-and-drop/upload.action | userName: gerald | action: upload | referer: https://host.example.com/confluence/pages/resumedraft.action?draftId=84646070&draftShareId=dfeae20b-393a-423f-aa08-400c195dcc52& | traceId: 0620767445f8d8c4
2024-05-07 09:54:28,060 WARN [document-conversion-sandbox-launcher-3] [impl.util.sandbox.SandboxProcess] startIfDead Sandbox 0 has died
-- url: /confluence/rest/documentConversion/latest/conversion/thumbnail/results | userName: gerald | referer: https://host.example.com/confluence/pages/resumedraft.action?draftId=84646070&draftShareId=dfeae20b-393a-423f-aa08-400c195dcc52& | traceId: 192e9486318c337d
2024-05-07 09:54:28,060 WARN [document-conversion-sandbox-launcher-3] [impl.util.sandbox.SandboxProcess] startIfDead Attempting to restart the sandbox 0
-- url: /confluence/rest/documentConversion/latest/conversion/thumbnail/results | userName: gerald | referer: https://host.example.com/confluence/pages/resumedraft.action?draftId=84646070&draftShareId=dfeae20b-393a-423f-aa08-400c195dcc52& | traceId: 192e9486318c337d
2024-05-07 09:54:28,066 WARN [ForkJoinPool.commonPool-worker-3] [plugins.conversion.impl.LocalFileSystemConversionResultSupplier] lambda$performConversionInSandbox$2 Error when performing conversion com.atlassian.confluence.plugins.conversion.impl.LocalFileSystemConversionResultSupplier$3@11fc66d6[attachment=/download/attachments/50331658/2024-04-18%20Report%20SC.pdf?version=1&modificationDate=1715068329507&api=v2,conversionType=THUMBNAIL] in the sandbox
java.util.concurrent.CompletionException: com.atlassian.confluence.util.sandbox.SandboxTimeoutException: Sandbox request has been killed because it exceeded time limit of 120 seconds
at java.base/java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:315)
at java.base/java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:320)
at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1770)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
at java.base/java.lang.Thread.run(Thread.java:840)
Caused by: com.atlassian.confluence.util.sandbox.SandboxTimeoutException: Sandbox request has been killed because it exceeded time limit of 120 seconds
at com.atlassian.confluence.impl.util.sandbox.SandboxProcess.tryToThrowSpecificException(SandboxProcess.java:171)
at com.atlassian.confluence.impl.util.sandbox.SandboxProcess.execute(SandboxProcess.java:139)
at com.atlassian.confluence.impl.util.sandbox.SandboxLocalProcessPool.execute(SandboxLocalProcessPool.java:107)
at com.atlassian.confluence.impl.util.sandbox.ConfluenceSandboxPoolFactory$LazySandbox.execute(ConfluenceSandboxPoolFactory.java:70)
at com.atlassian.confluence.impl.util.sandbox.DefaultSandbox.execute(DefaultSandbox.java:41)
at com.atlassian.confluence.plugins.conversion.impl.sandbox.LocalDocumentConversionSandbox.execute(LocalDocumentConversionSandbox.java:66)
at com.atlassian.confluence.plugins.conversion.impl.sandbox.LocalDocumentConversionSandbox.execute(LocalDocumentConversionSandbox.java:59)
at com.atlassian.confluence.plugins.conversion.impl.sandbox.DelegatingDocumentConversionSandbox.execute(DelegatingDocumentConversionSandbox.java:47)
at com.atlassian.confluence.plugins.conversion.impl.LocalFileSystemConversionResultSupplier.lambda$performConversionInSandbox$1(LocalFileSystemConversionResultSupplier.java:227)
at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1768)
... 3 more
Caused by: java.io.EOFException: error deserialize sandbox message
at com.atlassian.confluence.impl.util.sandbox.SandboxMessage.receiveMessage(SandboxMessage.java:50)
at com.atlassian.confluence.impl.util.sandbox.SandboxProcess.receiveMessage(SandboxProcess.java:227)
at com.atlassian.confluence.impl.util.sandbox.SandboxProcess.execute(SandboxProcess.java:136)
... 11 more
2024-05-07 09:54:28,067 WARN [ForkJoinPool.commonPool-worker-3] [plugins.conversion.impl.FileSystemConversionState] markAsError Creating error file: /var/atlassian/application-data/confluence/shared-home/dcl-thumbnail/158/81/50331658/352944134_1.err

I already went through these KB:

- https://confluence.atlassian.com/confkb/pdf-macro-failed-to-generate-the-thumbnail-image-1079348159.html

converting documents is not an option and IMO disabling the memory guard is not really an option either.

Instead I went with this KB article:

- https://confluence.atlassian.com/doc/document-conversion-for-confluence-data-center-952624318.html

and increased the timeout from the default 30 first to 60 and later to 120 seconds. This didn't help either.

JAVA_TOOL_OPTIONS: ' -Duser.timezone="Europe/Berlin" -Dconfluence.document.conversion.fontpath=/usr/share/fonts/truetype/msttcorefonts/ -Dconversion.sandbox.java.options=-Dconfluence.document.conversion.slides.convert.timeout=120 -Ddocument.conversion.sandbox.request.time.limit.secs=120 '

The .err files mentioned in the error messages are all empty, no help from there either.

The documents I used to test are a converted PPTX file with 6 slides and a pptx file directly, both files only around 240KB in size, so I don't think the file size is an issue. All three instances are running in the official Docker container with exactly the same options.

I also already tried uploading files in safe mode, which had the same result. So no installed add-on is responsible either.

Sadly, the problem only appears on the instance that is running a community license, so I can't open a support request for it.

Are there more log files I can take a look at, or can I increase the log verbosity for the process that is responsible for the thumbnail generation?

Update 2024-06-24

Neither the update to 8.9.2 nor to 8.9.3 resolved the issue. Am I the only one with this issue?

Update 2024-06-25

Other tries to solve the issue:

• Increased conversion.sandbox.memory.limit.megabytes from the default value of 512 to 1024 MB
• Increased Java heap space from 6GB to 8GB (I found more errors regarding heap space in the logs)

[Gerald Schneider]

I disabled the external process pool for document conversion and now the previews are generated again.

Nevertheless I'd prefer to solve the original problem and would be happy to get some insight.