System.DmlException: Upsert failed. First exception on row 0; first error: DUPLICATE_VALUE, duplicate value found
122501
Why does upsert cause a DUPLICATE_VALUE error?
124496
Database.SaveResult.getId() returns null
102497
Inserting text gives objectcollection error
59517
FATAL_ERROR|System.QueryException: List has no rows for assignment to SObject
67443
How to prevent duplicate records being inserted with SqlBulkCopy when there is no primary key
35103
Exeception on After Insert, Record is read only
68222
Reference to undeclared entity exception while working with XML
112077
How to check if a value already exists to avoid duplicates?
38371
How to UPSERT (MERGE, INSERT ... ON DUPLICATE UPDATE) in PostgreSQL?
68681
concurrentModificationException
76792
System.UnexpectedException: Invalid parameter value for parameter "Decryption Exception"
130341
SQL Insert Statement Persists Two Records When I Need Just One
34058
How to debug the mysterious "duplicate value found:  duplicates value on record with id: " error
46089
Fix for Hibernate error "Use of the same entity name twice"
102259
Custom Validation using Trigger throwing System.FinalException: SObject row does not allow errors
91860
Error 1022 - Can't write; duplicate key in table
140940
java.sql.SQLException: No data found