We are getting the following error upon uploading an xls sheet with 300 records

There's a 60 mns non-configurable limit for unattended nodes to complete. If this limit is hit you will get the following alert:

"The amount of time allocated for the completion of an unattended activity was insufficient to allow the activity to complete."

if you are seeing an error within the first 10 minutes then your assumption is not accurate enough, and the node is not timing out there should be something else.

This smart service generates a very generic alert that asks you to check the application-server.log for more details, my suggestion is the same, review the application-server.log and pay especial attention to the "Caused by" clauses in the stack trace to determine the root cause.

Yup, it has timed out a lot longer after receiving this error ...

What exception is shown in the application-server.log? Please upload it to this post.

We are using a cloud instance. Where I can find this file?

Please check the Log Files section from the following documentation:
forum.appian.com/.../Appian_Cloud_Web_Administration.html

I can not find this file under "Directory Listing For /logs/". Any other suggestions?

My apologies, I forgot to tell you that in cloud instances the file is called jboss1-stdOut.log.YYYY-MM-DD. Review jboss1-stdOut.log.YYYY-MM-DD.log and pay especial attention to the "Caused by" clauses in the stack trace to determine the root cause.

08:32:36,433 INFO [stdout] (ajp-/0.0.0.0:8009-14) Caused by: java.lang.NullPointerException: A null parameter has been passed as parameter 1.
08:32:36,433 INFO [stdout] (ajp-/0.0.0.0:8009-14)           at com.appiancorp.core.expr.fn.Signature.nullCheck(Signature.java:328)
08:32:36,433 INFO [stdout] (ajp-/0.0.0.0:8009-14)           at com.appiancorp.core.expr.fn.Function.nullCheck(Function.java:158)
08:32:36,433 INFO [stdout] (ajp-/0.0.0.0:8009-14)           at com.appiancorp.core.expr.fn.Function.nullCheck(Function.java:154)
08:32:36,433 INFO [stdout] (ajp-/0.0.0.0:8009-14)           at com.appiancorp.core.expr.fn.Signature.eval(Signature.java:136)
08:32:36,433 INFO [stdout] (ajp-/0.0.0.0:8009-14)           at com.appiancorp.core.expr.fn.Function.eval0(Function.java:44)
08:32:36,433 INFO [stdout] (ajp-/0.0.0.0:8009-14)           at com.appiancorp.core.expr.Evaluable.eval(Evaluable.java:154)
08:32:36,433 INFO [stdout] (ajp-/0.0.0.0:8009-14)           at com.appiancorp.core.expr.tree.FunctionCall.evalEvaluable(FunctionCall.java:283)
08:32:36,433 INFO [stdout] (ajp-/0.0.0.0:8009-14)           ... 151 more

Here is the log ... the caused by was received a few minutes after the other errors were thrown ...

Please attach the complete log for review.