Just for Support's cross-reference: the thread with exactly same problem https://community.smartbear.com/t5/TestComplete-Questions/TestComplete-Test-Adapter-v15-53-9-issues-running-tests-in/td-p/254356
Thank you for your suggestion.
https://stackoverflow.com/questions/72946728/yaml-specifying-a-fully-qualified-azure-task-version
and
https://stackoverflow.com/questions/72946728/yaml-specifying-a-fully-qualified-azure-task-version
sounded promising, but failed for me with this error on pipeline validation or if started:
"A task is missing. The pipeline references a task called 'InstallTestCompleteAdapter'. This usually indicates the task isn't installed, and you may be able to install it from the Marketplace: https://marketplace.visualstudio.com. (Task version 1.15040.421, job '[skipped]', step ''.)"
