Internal error
An unexpected internal error has occurred. Please try to repeat your last steps; if this error recurs, send an email to datawiz@leibniz-psychology.org and add the error message as well as a description of the last steps you have done so that we can reproduce and fix the error.
Exception: Failed to convert value of type 'java.lang.String' to required type 'java.util.Optional'; nested exception is org.springframework.core.convert.ConversionFailedException: Failed to convert from type [java.lang.String] to type [@org.springframework.web.bind.annotation.PathVariable java.lang.Long] for value '' + project.id + ''; nested exception is java.lang.NumberFormatException: For input string: "'+project.id+'" @ org.springframework.web.method.annotation.AbstractNamedValueMethodArgumentResolver.resolveArgument(AbstractNamedValueMethodArgumentResolver.java:132)
