When you migrate huge number of projects using the migration tool, you receive error "Service call failed" in simulation phase.
SAP Business ByDesign
Reproducing the Issue
1. Go to Business Configuration WoC
2. Search for Migration of Projects
3. Select Migrate projects using the migration tool.
4. Select Execute Migration Step by Step
Then in step 3 simulation import, error occurred: Service call failed
The issue might be due to high number of tasks that is used within that project.
Please check the sizing assessment tool: https://partneredge.sap.com/en/library/assets/products/ent_mng/byd/sell/tools_assets/pp_form_byd_epq.html. You can download it and enter the number of tasks part (4) Sizing "Maximum # of Tasks per project. Please check the size and split the migration file.
Migration of Projects , KBA , AP-PRO , Project Processing , How To