A probe by Holyrood’s IT staff found that after a software upgrade in March, 23 MSPs were unable to use the MAQA (Motions, Amendments, Questions, Answers) system to ask questions or table motions.
The problem - described as ‘intermittent’ - is thought to have affected members with surnames in the latter half of the alphabet including Scottish Liberal Democrat leader Willie Rennie, Mid Scotland and Fife Conservative MSP Liz Scott and Scottish Labour justice spokesman Graeme Pearson.
A letter from Holyrood chief executive Paul Grice sent to all MSPs, described the situation as ‘clearly unacceptable’ before apologising to those affected.
Mr Grice said: “An initial workaround to the software issue was put in place for the draw which took place yesterday.
“This involved a manual intervention by staff to ensure that all names submitted were included in the draw.
“The next step will be to replace the software.
“The replacement software will include additional audit functionality as a means to provide assurance that all participating names have been picked up by the system before they are randomised and drawn.
“It is expected that, subject to rigorous testing, the new software will be in place in time for the draw on December 7.”
The software’s main task is to randomly draw MSPs’ names for general and portfolio questions, and is understood to have affected up to 12 out of the 27 weeks of business since March 2015.
There are 30 members with surnames in the latter half of the alphabet, however seven MSPs - including First Minister Nicola Sturgeon, deputy First Minister John Swinney and Minister for Europe and International Development Humza Yousaf - were not affected due to their positions in cabinet.
Both Mr Grice and Presiding Officer Tricia Marwick have apologised for the issue.