SQLite DB Browser, can't modify column because trigger

Question

I want to add a column to a table with DB Browser but when I try to save, I get this error message:

Modifying this column failes. Error returned from database: Error renaming table 'sqlb_temp_table_19' to 'ClientData'.Message from database engine: error in trigger fki_ExclusionRoleClientDatas_ClientData_ID_ClientData_ID: no such table: main.ClientData (ALTER TABLE "main"."sqlb_temp_table_19" RENAME TO "ClientData")

The action I want to do is to add a column to 'ClientData' named 'RestartTime'. I don't have a table namend sqlb_temp_table_19 and I dont have 'ClientData'.Message.

The trigger exists with this content:

CREATE TRIGGER [fkd_ExclusionRoleClientDatas_ClientData_ID_ClientData_ID] Before Delete ON [ClientData] BEGIN DELETE FROM [ExclusionRoleClientDatas] WHERE ClientData_ID = OLD.ID; END

Whats is the error I get here?