Admido throws error - will not update records

[mtn]

Hello:
We have been using Admidio for quite sometime -- its excellent software that has revolutionized our society's handling of memberships.
Only now do we have our first issue.
When trying to update member records, we get an error message from Admidio saying that a field which was unfilled needs to be a number only.
We are running 3.3.10 with PHP 5.6 and MySQL 5.5.62
The fields that Admidio says must be numbers only are type DECIMAL and are optional (can be blank).
I should tell you that I have some custom scripts which directly edit the Admidio database, but these worked fine until the last few weeks.
At about the same time this first occurred, some members reported that they couldn't login -- though that may be unrelated.
I would welcome any suggestions or pointers to help me resolve this issue, though I realize that editing the database raises a lot of red flags.
Regards
Michael

[mtn]

I have figured out the problem -- we have a field for donations, which should be reset every year. One of my custom scripts set this to NULL instead of deleting the record. Once I deleted the records, Admidio worked fine.
So please ignore this thread
Michael