QlikView November 2017 (12.20): Failing reloads and BNF script reload mode

Reloads that were functioning fine in QlikView 11.20 or QlikView 12.x, begin to fail after an upgrade to QlikView November 2017.

After upgrading to QlikView November 2017, odd behavior may be seen with expressions, scripts, set analysis, etc.  Things like:

• Expression editor may throw an error
• Chart may show empty
• Chart may show "Incomplete visualization"
• Chart may show "Invalid dimension"
• And any other odd behavior that would mimic a change in the script (expression, set analysis, etc)
• Macros cannot be reloaded. See Macros stopped working after upgrade QlikView to 12.20 version

So far, we have seen this issue manifest with a few customers as a change in how single quotes and double quotes are being treated.
See article Quotes in Set Analysis change in behavior

Environment:

A new script reload mode, BNF, has been introduced.

A new script reload mode, BNF, has been introduced. In some unusual cases, users may need to disable the BNF reload mode using one of these methods.
As specified in the QlikView November 2017 release notes "we recommend disabling it only as a temporary action, in case you are investigating problems with the regular procedure".

This should not, therefore, considered as a permanent solution.
 

PLEASE NOTE: THE FOLLOWING SETTINGS WILL NOT WORK IN 12.30 (November 2018) OR HIGHER, SINCE THE ENGINE IS NOW BNF-ONLY. SCRIPTS WILL HAVE TO BE MODIFIED TO MATCH THE BACKUS-NAUR FORMALISM. SEE ALSO: QlikView April 2019 (12.40): disabling BNF no longer possible. This change was mentioned in the Release Notes for QlikView November 2018, but it was actually introduced in April 2019.

Disabling BNF reload mode on the local QlikView client:

Note: This flag has been disabled in 12.30 (November 2018). Resolving the problem will require a rewriting of the scripts, since the options to disable BNF won't work.

Update the QV.exe  Settings.ini file by adding the line EnableBnfReload=0 under the [Settings 7] tag for the default reload setting "EnableBnfReload".
By default, Settings.ini can be found in C:\%USER%\AppData\Roaming\QlikTech\QlikView​
 

Disabling BNF reload mode for the entire server :

Note: This flag has been disabled in 12.30 (November 2018). Resolving the problem will require a rewriting of the scripts, since the options to disable BNF won't work.

Update the QVB.exe  Settings.ini by adding the line EnableBnfReload=0 under the [Settings 7] tag for the default reload setting "EnableBnfReload". 
By default, the Settings.ini can be found in C:\Windows\System32\config\systemprofile\AppData\Roaming\QlikTech\QlikViewBatch. For more information please review Where to find the QlikView QVB settings file

Modify it to read:

[Settings 7]
EnableBnfReload=0

Disabling BNF reload mode for individual apps:

Add the ///$bnf off tag at the top of the script (it must be within the first 50 characters of the script). Reload the script.
It is a good idea to use the ///$bnf off tag as a troubleshooting step.  See if toggling this setting in the load script will cause a change in the suspect behavior.