Error during calculation of multi-scenario product system in OpenLCA (result display fails)

Question

Hello,

I'm working on a comparative LCA project in OpenLCA involving two scenarios:

• Scenario 1: Landfilling of organic waste

• Scenario 2: Biogas production in a treatment plant

Both scenarios are defined within the same product system using scenario modeling features (under the "Scenarios" tab). However, when I attempt to calculate impact results, no results are displayed, or the calculation only shows the reference process, while the other connected processes are ignored.

Here are the checks I’ve already done:

• All processes are correctly linked in the process chain graph (no visually isolated nodes).

• Each process has one reference flow and a consistent unit (e.g., kg or t).

• The impact method is assigned and enabled (EF 2.0).

• All intermediate flows have valid providers.

• The product system calculates correctly without the scenarios activated.

• Scenario configurations are saved and properly linked to modified processes.

Despite this, the system either:

• Calculates only one process (e.g., the initial waste input), or

• Fails to produce any result at all.

I have also tried recalculating the product system, reassigning impact methods, and validating all process exchanges.

My questions:

1. Are there known bugs or misconfigurations that could cause scenario-linked product systems to fail during LCIA calculation?

2. Could this issue be related to flow misalignment or a scenario cache problem?

3. Is there a recommended way to debug incomplete scenario calculations, such as logs or deep validation tools?

Thank you very much for any guidance, and I can provide screenshots or the .zolca file if needed.

Best regards,
Fatima Zahra Beraich

Answer 1

Hi Fatima, some questions to better understand: Which version are you using? Did you perform a validation of the database, what does it say? Are there any entries in the log file related to errors? Thank you!