KB-XXXX Process model version comparison fails with a generic error

Symptoms

When attempting to compare two versions of a process model, the following error appears:

Cannot compare versions. The process model does not exist, the versions have been deleted, or you do not have sufficient privileges to access its data.

In the application server log, an error similar to the following is observed:

2019-05-08 21:07:36,192 [ajp-nio-8009-exec-2243] ERROR com.appiancorp.core.expr.fn.info.LogLastExceptionFunction - Expression evaluation error at function a!dod_fwk_controller [line 14]: Error in a!forEach() expression during iteration 4: Expression evaluation error at function a!dod_fwk_createDiffSection [line 65]: Error in a!forEach() expression during iteration 1: Expression evaluation error at function a!dod_fwk_iterateComponents [line 48]: Error in a!forEach() expression during iteration 3: Expression evaluation error at function a!dod_fwk_sectionsGenerator [line 103]: Error in a!forEach() expression during iteration 1: Expression evaluation error at function a!dod_fwk_createDiffSection [line 65]: Error in a!forEach() expression during iteration 4: Expression evaluation error at function a!dod_fwk_createDiffSection [line 65]: Error in a!forEach() expression during iteration 4: Expression evaluation error at function a!dod_fwk_createDiffComponent [line 94]: Illegal newline character found in: =if(
isnull(pv!user),
pp!initiator,
pv!user
)_0
com.appiancorp.core.expr.exceptions.ExpressionRuntimeException$AppianExceptionProvider: Expression evaluation error at function a!dod_fwk_controller [line 14]: Error in a!forEach() expression during iteration 4: Expression evaluation error at function a!dod_fwk_createDiffSection [line 65]: Error in a!forEach() expression during iteration 1: Expression evaluation error at function a!dod_fwk_iterateComponents [line 48]: Error in a!forEach() expression during iteration 3: Expression evaluation error at function a!dod_fwk_sectionsGenerator [line 103]: Error in a!forEach() expression during iteration 1: Expression evaluation error at function a!dod_fwk_createDiffSection [line 65]: Error in a!forEach() expression during iteration 4: Expression evaluation error at function a!dod_fwk_createDiffSection [line 65]: Error in a!forEach() expression during iteration 4: Expression evaluation error at function a!dod_fwk_createDiffComponent [line 94]: Illegal newline character found in: =if(
isnull(pv!user),
pp!initiator,
pv!user
)_0 (APNX-1-4198-000)

Cause

This error is observed if any nodes use expressions containing line breaks in their assignment settings. The issue has been reported to the Appian Product Team as AN-133660.

Workaround

To ensure future versions of the model do not encounter issues:

1. Determine which node in the process model has an assignment expression that contains newlines
2. Modify the expression to remove any newlines
3. Save and publish the process model

Affected Versions

This article applies to Appian 19.1 and later.

Last Reviewed: August 2019