Verification -- Verification of Co-Simulation Algorithms Subject to Algebraic Loops and Adaptive Steps -- Automated Verification of Temporal Properties of Ladder Programs -- Spatial Model Checking for Smart Stations: Research Challenges -- Program Safety and Education -- Parametric Faults in Safety Critical Programs -- Modular Transformation of Java Exceptions Modulo Errors -- On education and training in formal methods for industrial critical systems -- (Event-)B Modeling and Validation -- Improving SMT Solver Integrations for the Validation of B and Event-B Models -- Standard Conformance-by-Construction with Event-B -- Formal Analysis -- Randomized Reachability Analysis in Uppaal: Fast Error Detection in Timed Systems -- Verifying the Mathematical Library of an UAV Autopilot with Frama-C -- Formal Analysis of the UNISIG Safety Application Intermediate Sub-Layer -- Tools -- ProB2-UI: A Java-based User Interface for ProB -- Intrepid: a Scriptable and Cloud-ready SMT-based Model Checker -- Merit and Blame Assignment with Kind 2 -- Test Generation and Probabilistic Verification -- PSY-TaLiRo: A Python Toolbox for Search-Based Test Generation for Cyber-Physical Systems -- Probabilistic Verification for Reliability of a Two-by-Two Network-on-Chip System.

This book constitutes the proceedings of the 26th International Workshop on Formal Methods for Industrial Critical Systems, FMICS 2021, which was held during August 24-26, 2021. The conference was planned to take place in Pairs, France. Due to the COVID-19 pandemic it changed to a virtual event. The 10 full papers and 6 short papers presented in this volume were carefully reviewed and selected from 31 submissions. The papers are organized in topical sections as follows: Verification, Program Safety and Education, (Event-)B Modeling and Validation, Formal Analysis, Tools, Test Generation and Probabilistic Verification.