Pupils were marked down for forgetting to dot an "i" in this year's Sats tests, headteachers claimed today.
But others still received the marks because the examiner added the dot for the pupil in red ink, the National Association of Head Teachers (NAHT) said.
The union urged heads to contact England's exams regulator, Ofqual, about marking inconsistencies as it published a list of problems raised by members.
It included concerns that wrong spellings had been marked right, while right spellings had been marked wrong.
Pupils with good writing skills had been marked down because of a "formulaic mark scheme which did not give recognition for flair and creativity", the NAHT said.
Heads also raised concerns that there was little consistency in marking, there were clerical errors, and inadequate levels of care taken by some markers.
In one case, a headteacher reported that a child had been violently sick over her paper 34 minutes into a 45 minute exam, the union said.
The head rang a helpline for guidance and was asked if he knew what question the child had reached. He was then told the child could start a fresh paper but must complete it in 11 minutes.
The child had been taken home.
The NAHT said headteachers should write to Kathleen Tattersall, chair of Ofqual, because she had said she would listen to concerns over marking.
NAHT assistant secretary Ian Foster said: "The bureaucracy and stress surrounding these outmoded tests, compounded by clear examples of poor or inadequate marking, can be dispiriting for pupils and parents, and can potentially put school leaders' careers on the line, particularly if the school is in an Ofsted category, which may in itself be as a result of flawed data based on wrongly levelled marking."
Last year, just over a fifth of English papers taken by 14-year-olds were sent back for review, following the marking fiasco.
Appeals are not expected to be as high this year, although teaching unions have warned that as many as one in five results may be inaccurate.
There are usually more requests for reviews of English papers than other subjects, as it is harder to mark.
Sats tests in English, maths and science were taken by 11-year-olds at the end of May, and the results were delivered to schools on time at the beginning of July.
In an interview with the Press Association at that time, Ms Tattersall said: "Now the results are out, we will be listening to see if schools have particular concerns, any concerns that they raise."
The Qualifications and Curriculum Authority - the government body responsible for the tests, and new contractor Edexcel were under pressure to meet the deadline following last summer's delays.
Schools Secretary Ed Balls scrapped Sats for 14-year-olds last October, and the science test will be abolished from next year.
The NAHT and the National Union of Teachers (NUT) have announced plans to ballot over boycotting next year's Sats if they are not abolished.Reuse content