Mark Canes Blue Link Associates Limited President

After upgrade, most tasks work fine, but a handful of tasks fail, Two examples:

1.  Task fails with Object reference not set to an instance of an object when trying to create a variable with an initial value equal to a constant that does have a value. (But in other tasks that constant is used successfully.)
2. Task that opens and decodes a JSON file returns no data (as if the JSON file is empty) even though it is not empty - and another task is able to use the same JSON file.

We have had to revert to 11.3.10.65 as too many tasks were failing, and we were unable to debug.

Is this a known issue after upgrading? If so, what's the solution? At some point I'd like to upgrade to a new version (now 11.7) but cannot afford to have the same thing happen again. Any help would be appreciated.