We are migrating our mxd from existing host to a new one, once it is done. We found that all query layer in the mxd are no longer working, It seems that Set Data Source(s) in ArcCatalog not for query layer and We had to edit these layer one by one. Although there are pop up showing "Underlying DBMS did not accept username/password" before the edit. The database connection itself seems fine. By select the right connection available in the drop down list, then click "Validate"
We can click "Next" to continue and have that layer fixed. The tricky parts is, most of these query layers get stuck on "Validate", the "Next" button would not enabled and there are no feedback shown. Did the validation failed in some way?