Camunda send task stop working


could anyone help me with a problem that occurred me lately? Always when I try to pass through send task, i get this error message:
" An error happened while submitting the task form : Cannot submit task form fa074e43-af83-11e9-9d9d-d29cc9d73fa5: ENGINE-09008 Exception while instantiating class ‘com.camunda.demo.ErasmusTUWien.UploadApplication’: ENGINE-09017 Cannot load class ‘com.camunda.demo.ErasmusTUWien.UploadApplication’: com.camunda.demo.ErasmusTUWien.UploadApplication"

I already tried everything that I found in related topics, but nothing has helped me so far. I am pretty sure that I hadn’t changed anything in the folder either model before it stopped working (it was working before properly and also models that I didn’t change since then are still fine, but with new one, I get the same issue).
I use Eclipse and Apache Tomcat.

Thank you for any help.

can you upload your model?
And check the classpath for the class com.camunda.demo.ErasmusTUWien.UploadApplication .
Also, what is your environment setup? Clustering model, multi tenancy or single node?

I checked the classpath and it should be correct.
Single node

process.bpmn (25.5 KB)