5250 error 0020: Enter key not allowed in field

What it means

Some fields are right-adjusted. The digits you type start at the left of the field, and the display station moves them to the right end when you finish. Signed numeric fields (shift S in the DDS) work this way by default, with blank fill. Other fields get it from CHECK(RB) or CHECK(RZ), or the matching AUTO(RAB) and AUTO(RAZ), which fill the left side with blanks or zeros.

IBM's DDS reference says the adjustment happens only when you press Field Exit, Field+ or Field-. Type 25 in a five-position quantity field and press Enter at once, and the field still holds 25 followed by three blanks, which isn't the number you meant. So the display station refuses Enter, locks the keyboard and shows 0020. The cursor stays where it was.

For a signed numeric field, IBM notes that Enter is fine if you typed nothing in the field. The error comes only once you have keyed digits and haven't finished the field.

Common causes

• You typed a number in a quantity or amount field and pressed Enter without Field Exit.
• Your emulator maps Enter and Field Exit to different keys than the terminal or emulator you are used to, so the key you think of as Field Exit sends Enter.
• The field doesn't look numeric. A document or reference number with CHECK(RZ) behaves the same way, because it also right-adjusts.

How to find the problem

1. Look at the cursor. It is still in the field you typed in, and the value hasn't moved to the right.
2. Press Help while 0020 is on the error line to see the system's text for the error.
3. In the display file source, check the field for shift S in position 35, CHECK(RB), CHECK(RZ), AUTO(RAB) or AUTO(RAZ).

How to fix it

• Press Reset (also called Error Reset) to free the keyboard. In many PC emulators Reset is the left Ctrl key by default. Then press Field Exit (or Field- for a negative value) and press Enter.
• Make Field Exit a habit after every number. Which key sends it depends on your emulator's keyboard map.
• Check the emulator's keyboard map if 0020 keeps appearing. Most emulators let you choose which key sends Enter and which sends Field Exit.
• For programmers, if right adjustment doesn't matter for a field, IBM's DDS reference says a numeric-only field (shift Y) without CHECK(RB) or CHECK(RZ) can be left with any key. Recreate the display file with CRTDSPF after the change.
• For programmers, keep CHECK(RB) or CHECK(RZ) where the value must be aligned, for example key fields that are compared or zero-padded codes, and tell users to finish those fields with Field Exit.

Technical reviewer: Albert Joseph, WND Software.

Last reviewed 2026-10-18 by the WND Software team. Written in our own words. For the full reference, check IBM’s 3270 or 5250 display documentation.