| Subject | Welsh | English |
| comp., MS | bar gwall | error bar (Usually used in statistical or scientific data, an error bar shows the potential error or degree of uncertainty relative to each data marker in a series) |
| comp., MS | cod gwall | error code (A return code that begins with E_ or DB_E_ and indicates that the method failed completely and was unable to do any useful work. Usually indicates a programming error) |
| comp., MS | cod y gwall | error code (One of four fields of an SCODE. It is a unique number that is assigned to represent the error or warning) |
| comp., MS | gwall cystrawen | syntax error (An error in the grammatical structure of the code or expression) |
| comp., MS | gwall wrth gysoni | sync error (A problem that prevents sync from completing. Sync errors are typically caused by problems with the device, network folder, or other computer you are trying to sync with) |
| comp., MS | gwerth gwall | error value (A value shown in Excel when there is an error in a formula, for example VALUE! or REF!) |