I'm getting the above error message. However, the page in question does indeed have a tag with runat="server" attribute on it (at design time) and the control
css-color
angular2-ngcontent
scikit-image
group
affix
aquafold
spresense
react-360
github
ora-04091
dwscript
couchbase-sync-gateway
filter-validate-email
.net-core-authorization
multi-upload
jquery-ui-css-framework
zombie.js
time-management
cognex
writeonly
webdatagrid
declarative-authorization
android-device-manager
exasol
file-properties
placement
android-pageradapter
discord-jda
cpu-cache
catiledlayer